Preliminary PET imaging of [11C]evobrutinib in mouse models of colorectal cancer, SARS-CoV-2, and lung damage: Radiosynthesis via base-aided palladium-NiXantphos-mediated 11C-carbonylation

Evobrutinib is a second-generation, highly selective, irreversible Bruton's tyrosine kinase (BTK) inhibitor that has shown efficacy in the autoimmune diseases arthritis and multiple sclerosis. Its development as a positron emission tomography (PET) radiotracer has potential for in vivo imaging of BTK in various disease models including several cancers, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), and lipopolysaccharide (LPS)-induced lung damage. Herein, we report the automated radiosynthesis of [11C]evobrutinib using a base-aided palladium-NiXantphos-mediated 11C-carbonylation reaction. [11C]Evobrutinib was reliably formulated in radiochemical yields of 5.5 ± 1.5% and a molar activity of 34.5 ± 17.3 GBq/μmol (n = 12) with 99% radiochemical purity. Ex vivo autoradiography studies showed high specific binding of [11C]evobrutinib in HT-29 colorectal cancer mouse xenograft tissues (51.1 ± 7.1%). However, in vivo PET/computed tomography (CT) imaging with [11C]evobrutinib showed minimal visualization of HT-29 colorectal cancer xenografts and only a slight increase in radioactivity accumulation in the associated time-activity curves. In preliminary PET/CT studies, [11C]evobrutinib failed to visualize either SARS-CoV-2 pseudovirus infection or LPS-induced injury in mouse models. In conclusion, [11C]evobrutinib was successfully synthesized by 11C-carbonylation and based on our preliminary studies does not appear to be a promising BTK-targeted PET radiotracer in the rodent disease models studied herein.

11C-Fixation Techniques

This protocol describes the application of cyclotron-generated [11C]CO2 fixation reactions for direct 11C-carboxylation reactions and [11C]CO for 11C-carbonylations. Herein we describe one-pot methods wherein the radioactive gas is first trapped in a reaction mixture at room temperature and atmospheric pressure prior to the radiolabeling reactions. Such procedures are widely applicable to numerous small molecules to form 11C-labeled carboxylic acids, amides, esters, ketones, oxazolidinones, carbamates, and ureas. The steps for 11C-fixation techniques described herein are tailored for a commercial automated synthesis unit and are readily adapted for routine radiopharmaceutical production.

First-in-Human PET Imaging of [18F]SDM-4MP3: A Cautionary Tale

[18F]SynVesT-1 is a PET radiopharmaceutical that binds to the synaptic vesicle protein 2A (SV2A) and serves as a biomarker of synaptic density with widespread clinical research applications in psychiatry and neurodegeneration. The initial goal of this study was to concurrently conduct PET imaging studies with [18F]SynVesT-1 at our laboratories. However, the data in the first two human PET studies had anomalous biodistribution despite the injected product meeting all specifications during the prerelease quality control protocols. Further investigation, including imaging in rats as well as proton and carbon 2D-NMR spectroscopic studies, led to the discovery that a derivative of the precursor had been received from the manufacturer. Hence, we report our investigation and the first-in-human study of [18F]SDM-4MP3, a structural variant of [18F]SynVesT-1, which does not have the requisite characteristics as a PET radiopharmaceutical for imaging SV2A in the central nervous system.

Spirocyclic Iodonium Ylides for Fluorine-18 Radiolabeling of Non-Activated Arenes: From Concept to Clinical Research

Positron emission tomography (PET) is a powerful imaging tool for drug discovery, clinical diagnosis, and monitoring of disease progression. Fluorine-18 is the most common radionuclide used for PET, but advances in radiotracer development have been limited by the historical lack of methodologies and precursors amenable to radiolabeling with fluorine-18. Radiolabeling of electron-rich (hetero)aromatic rings remains a long-standing challenge in the production of PET radiopharmaceuticals. In this personal account, we discuss the history of spirocyclic iodonium ylide precursors, from inception to applications in clinical research, for the incorporation of fluorine-18 into complex non-activated (hetero)aromatic rings.

In Silico Discovery and Subsequent Characterization of Potent 4R-Tauopathy Positron Emission Tomography Radiotracers

A chemical fingerprint search identified Z3777013540 (1-(5-(6-fluoro-1H-indol-2-yl)pyrimidin-2-yl)piperidin-4-ol; 1) as a potential 4R-tau binding ligand. Binding assays in post-mortem Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) brain with [3H]1 provided KD (nM) values in AD = 4.0, PSP = 5.1, and CBD = 4.5. In vivo positron emission tomography (PET) imaging in rats with [18F]1 demonstrated good brain penetration and rapid clearance from normal brain tissues. A subsequent molecular similarity search using 1 as the query revealed an additional promising compound, Z4169252340 (4-(5-(6-fluoro-1H-indol-2-yl)pyrimidin-2-yl)morpholine; 21). Binding assays with [3H]21 provided KD (nM) values in AD = 1.2, PSP = 1.6, and CBD = 1.7 and lower affinities for binding aggregated α-synuclein and amyloid-beta. PET imaging in rats with [18F]21 demonstrated a higher brain penetration than [18F]1 and rapid clearance from normal brain tissues. We anticipate that 1 and 21 will be useful for the identification of other potent novel 4R-tau radiotracers.

Reactive Palladium-Ligand Complexes for 11C-Carbonylation at Ambient Pressure: A Breakthrough in Carbon-11 Chemistry

The Pd-Xantphos-mediated ¹¹C-carbonylation protocol (also known as the "Xantphos- method"), due to its simplistic and convenient nature, has facilitated researchers in meeting a longstanding need for preparing ¹¹C-carbonyl-labeled radiopharmaceuticals at ambient pressure for positron emission tomography (PET) imaging and drug discovery. This development could be viewed as a breakthrough in carbon-11 chemistry, as evidenced by the rapid global adoption of the method by the pharmaceutical industry and academic laboratories worldwide. The method has been fully automated for the good manufacturing practice (GMP)-compliant production of novel radiopharmaceuticals for human use, and it has been adapted for "in-loop" reactions and microwave technology; an impressive number of ¹¹C-labeled compounds (>100) have been synthesized. Given the simplicity and efficiency of the method, as well as the abundance of carbonyl groups in bioactive drug molecules, we expect that this methodology will be even more widely adopted in future PET radiopharmaceutical research and drug development.

Work incapacity and psychiatric patient care following attempted suicide - a cohort study of 65 097 Swedish twins

BACKGROUND

Research is scarce on the role of familial factors and previous psychiatric care on the association between suicide attempt and future work incapacity as well as deterioration in mental health. We aimed to investigate the associations between suicide attempt and sickness absence, disability pension and psychiatric patient care and to study the influence of previous psychiatric care and familial factors (genetics and shared environment) on the associations.

METHODS

The study included 65 097 twins living in Sweden on 31st of December 2006, aged 19-60 years. The twins were followed 2007-2013 regarding sickness absence, disability pension, inpatient care or specialized outpatient care for a mental diagnosis. Cox regression models were performed for the whole sample, and conditional models for discordant twin pairs. The analyses were also stratified by psychiatric care before 2007.

RESULTS

We found that suicide attempt predicted sickness absence, disability pension, and future mental diagnosis among the whole sample. The discordant twin pair analyses showed that the association between suicide attempt and sickness absence or disability pension was influenced by familial factors. Stratified analyses of individuals with or without psychiatric care before 2007 showed that previous psychiatric care had some impact on the associations.

CONCLUSIONS

A suicide attempt is a risk factor for work incapacity and psychiatric patient care. Familial factors and previous psychiatric care play a role in the associations between attempting suicide and work incapacity as well as psychiatric patient care. These factors are important when developing measures preventing work incapacity among those with a suicide attempt.

Strategies for designing novel PET radiotracers to cross the blood brain barrier

Positron emission tomography (PET) is a powerful tool for imaging biological processes in the central nervous system (CNS). Designing PET radiotracers capable of crossing the blood-brain barrier (BBB) remains a major challenge. In addition to being brain-penetrant, a quantifiable CNS PET radiotracer must have high target affinity and selectivity, appropriate pharmacokinetics, minimal non-specific binding, negligible radiometabolites in the brain, and must be amenable to labelling with ¹¹ C or ¹⁸ F. This review aims to give an overview of some of the critical physicochemical and biochemical contributors specific for CNS PET radiotracer design and how they can differ from pharmaceutical drug development, including in vitro assays, in silico predictions and in vivo studies, with examples for how such methods can be implemented to optimize brain uptake of radiotracers based on experiences from our neuroimaging program.

Recent Developments in Carbon-11 Chemistry and Applications for First-In-Human PET Studies

Positron emission tomography (PET) is a molecular imaging technique that makes use of radiolabelled molecules for in vivo evaluation. Carbon-11 is a frequently used radionuclide for the labelling of small molecule PET tracers and can be incorporated into organic molecules without changing their physicochemical properties. While the short half-life of carbon-11 (¹¹C; t_½ = 20.4 min) offers other advantages for imaging including multiple PET scans in the same subject on the same day, its use is limited to facilities that have an on-site cyclotron, and the radiochemical transformations are consequently more restrictive. Many researchers have embraced this challenge by discovering novel carbon-11 radiolabelling methodologies to broaden the synthetic versatility of this radionuclide. This review presents new carbon-11 building blocks and radiochemical transformations as well as PET tracers that have advanced to first-in-human studies over the past five years.

Ring-opening of non-activated aziridines with [11C]CO2 via novel ionic liquids

Novel ionic liquids based on DBU and DBN halide salts were developed as a catalytic system for ring-opening of non-activated aziridines with [¹¹C]CO₂. The ability of ionic liquids to activate aziridines represents a simple methodology for the synthesis of ¹¹C-carbamates and can be extended for CO₂-fixation in organic and radiochemistry.

Novel ionic liquids based on DBU and DBN halide salts were developed as a catalytic system for ring-opening of non-activated aziridines with [¹¹C]CO₂.

Preliminary Evaluations of [11C]Verubulin: Implications for Microtubule Imaging With PET

[¹¹C]Verubulin (a.k.a.[¹¹C]MCP-6827), [¹¹C]HD-800 and [¹¹C]colchicine have been developed for imaging microtubules (MTs) with positron emission tomography (PET). The objective of this work was to conduct an in vivo comparison of [¹¹C]verubulin for MT imaging in mouse and rat brain, as well as an in vitro study with this radiotracer in rodent and human Alzheimer’s Disease tissue. Our preliminary PET imaging studies of [¹¹C]verubulin in rodents revealed contradictory results between mouse and rat brain uptake under pretreatment conditions. In vitro autoradiography with [¹¹C]verubulin showed an unexpected higher uptake in AD patient tissue compared with healthy controls. We also conducted the first comparative in vivo PET imaging study with [¹¹C]verubulin, [¹¹C]HD-800 and [¹¹C]colchicine in a non-human primate. [¹¹C]Verubulin and [¹¹C]HD-800 require pharmacokinetic modeling and quantification studies to understand the role of how these radiotracers bind to MTs before translation to human use.

Effects of lung tissue characterization in radiotherapy of breast cancer under deep inspiration breath hold when using Monte Carlo dosimetry

PURPOSE

To investigate the sensitivity of Monte Carlo (MC) calculated lung dose distributions to lung tissue characterization in external beam radiotherapy of breast cancer under Deep Inspiration Breath Hold (DIBH).

METHODS

EGSnrc based MC software was employed. Mean lung densities for one hundred patients were analysed. CT number frequency and clinical dose distributions were calculated for 15 patients with mean lung density below 0.14 g/cm³. Lung volume with a pre-defined CT numbers was also considered. Lung tissue was characterized by applying different CT calibrations in the low-density region and air-lung tissue thresholds. Dose impact was estimated by Dose Volume Histogram (DVH) parameters.

RESULTS

Mean lung densities below 0.14 g/cm³ were found in 10% of the patients. CT numbers below -960 HU dominated the CT frequency distributions with a high rate of CT numbers at -990 HU. Mass density conversion approach influenced the DVH shape. V_4Gy and V_8Gy varied by 7% and 5% for the selected patients and by 9% and 3.5% for the pre-defined lung volume. V_16Gy and V_20Gy, were within 2.5%. Regions above 20 Gy were affected. Variations in air- lung tissue differentiation resulted in DVH parameters within 1%. Threshold at -990 HU was confirmed by the CT number frequency distributions.

CONCLUSIONS

Lung dose distributions were more sensitive to variations in the CT calibration curve below lung (inhale) density than to air-lung tissue differentiation. Low dose regions were mostly affected. The dosimetry effects were found to be potentially important to 10% of the patients treated under DIBH.

Radiosynthesis, In Vitro and In Vivo Evaluation of [18F]CBD-2115 as a First-in-Class Radiotracer for Imaging 4R-Tauopathies

CBD-2115 was selected from a library of 148 compounds based on a pyridinyl-indole scaffold as a first-in-class 4R-tau radiotracer. In vitro binding assays showed [³H]CBD-2115 had a K_D value of 6.9 nM and a nominal B_max of 500 nM in 4R-tau expressing P301L transgenic mouse tissue. In binding assays with human brain tissue homogenates, [³H]CBD-2115 has a higher affinity (4.9 nM) for progressive supranuclear palsy specific 4R-tau deposits than [³H]flortaucipir (45 nM) or [³H]MK-6240 (>50 nM). [¹⁸F]CBD-2115 was reliably synthesized (3-11% radiochemical yield with molar activity of 27-111 GBq/μmol and >97% radiochemical purity). Dynamic PET imaging was conducted in mice, rats, and nonhuman primates, and all species showed initial brain uptake of 0.5-0.65 standardized uptake value with fast clearance from normal tissues. [³H]CBD-2115 could be a useful lead radioligand for further research in 4R-tauopathies, and PET radiotracer development will focus on improving brain uptake and binding affinity.

The Swedish National Airway Register (SNAR): development, design and utility to date

Background

The Swedish National Airway Register (SNAR) was initiated in 2013 to ensure and improve the quality of care for patients with asthma and COPD.

Aim

To describe the development and design of SNAR, and to study the 2019 data to evaluate its potential utility related to improvement of quality of care.

Methods

SNAR includes data from patients with asthma (both children and adults) and COPD from primary, secondary and tertiary care, and also, for COPD inpatient care. Data on diagnostic investigations (e.g. spirometry, blood sample, skin prick test), symptom-scores, comorbidities and prescribed treatments are registered. The registrations are entered manually by healthcare professionals, or directly transferred from electronic medical records to a web-based platform.

Results

In 2019, 1000 clinics participated and data were directly transferred by about 88% of them. The register included data on 205,833 patients with asthma and 80,372 with COPD (of these, 5% had both diagnoses). Registrations of new patients and follow-up visits from primary and secondary/tertiary care in 2019 were completed for 75,707 patients with asthma (11,818 children <12 yr, 6545 adolescents 12–17 yr, and 57,344 adults >17 yr) and 38,117 with COPD. Depending on age and disease group, 43–77% had performed spirometry, 36–65% Asthma Control Test, and 60% COPD Assessment Test. The prevalence of current smoking was about 2% in adolescents, 10% in adults with asthma, and 34% in COPD. For these, smoking cessation support was offered to 27%, 38% and 51%, respectively. Overall, limited data were available on investigation of allergy, 6-min walk test, patient education and written treatment plans. Regarding asthma, sex-differences in disease management were evident.

Conclusion

SNAR has cumulatively registered data from over 270,000 individuals, and the register is important for patients, caregivers, authorities, politicians and researchers to evaluate the effect of treatment and to ensure high and equal quality of care nationwide.

Non-response did not affect prevalence estimates of asthma and respiratory symptoms - results from a postal questionnaire survey of the general population

BACKGROUND

A high participation rate is warranted in order to ensure validity in surveys of the general population. However, participation rates in such studies have declined during the last decades.

OBJECTIVE

To evaluate the reasons for and potential effects of non-response in a large population-based survey about asthma and respiratory symptoms in Northern Sweden.

METHODS

Within the Obstructive Lung Disease In Norrbotten (OLIN) studies, a random sample of 12,000 adults aged 20-79 was invited to a postal questionnaire survey about asthma, allergic rhino-conjunctivitis and respiratory symptoms in 2016. Three reminders were sent. A random sample of 500 non-responders was invited to a telephone interview.

RESULTS

The participation rate in the initial mailing was 41.4%, and 9.2%, 5.0%, and 2.6% in the subsequent three reminders and totally 58.3% (n = 6854) responded. Of 500 non-responders selected for telephone interviews, 320 were possible to reach and 272 participated. Male sex, younger age, and current smoking were associated with both late and non-response. The prevalence of asthma and most respiratory symptoms did not differ significantly between responders and non-responders while allergic rhino-conjunctivitis and smoking was more common among non-responders. Reminders increased the participation rate but did not alter risk ratios for smoking and occupational exposures. Reasons for non-response were mainly lack of time and having forgotten to answer.

CONCLUSIONS

With a response rate of 58.3%, neither the prevalence estimates of asthma, respiratory symptoms nor the associations to risk factors were affected by non-response, while allergic rhino-conjunctivitis and smoking was underestimated in this Swedish population.

A description and qualitative comparison of the elements of heterogeneous bovine viral diarrhea control programs that influence confidence of freedom

For endemic infections in cattle that are not regulated at the European Union level, such as bovine viral diarrhea virus (BVDV), European Member States have implemented control or eradication programs (CEP) tailored to their specific situations. Different methods are used to assign infection-free status in CEP; therefore, the confidence of freedom associated with the "free" status generated by different CEP are difficult to compare, creating problems for the safe trade of cattle between territories. Safe trade would be facilitated with an output-based framework that enables a transparent and standardized comparison of confidence of freedom for CEP across herds, regions, or countries. The current paper represents the first step toward development of such a framework by seeking to describe and qualitatively compare elements of CEP that contribute to confidence of freedom. For this work, BVDV was used as a case study. We qualitatively compared heterogeneous BVDV CEP in 6 European countries: Germany, France, Ireland, the Netherlands, Sweden, and Scotland. Information about BVDV CEP that were in place in 2017 and factors influencing the risk of introduction and transmission of BVDV (the context) were collected using an existing tool, with modifications to collect information about aspects of control and context. For the 6 participating countries, we ranked all individual elements of the CEP and their contexts that could influence the probability that cattle from a herd categorized as BVDV-free are truly free from infection. Many differences in the context and design of BVDV CEP were found. As examples, CEP were either mandatory or voluntary, resulting in variation in risks from neighboring herds, and risk factors such as cattle density and the number of imported cattle varied greatly between territories. Differences were also found in both testing protocols and definitions of freedom from disease. The observed heterogeneity in both the context and CEP design will create difficulties when comparing different CEP in terms of confidence of freedom from infection. These results highlight the need for a standardized practical methodology to objectively and quantitatively determine confidence of freedom resulting from different CEP around the world.

Potential for imaging the high-affinity state of the 5-HT1B receptor: a comparison of three PET radioligands with differing intrinsic activity

Background

Over the last decade, a few radioligands have been developed for PET imaging of brain 5-HT_1B receptors. The 5-HT_1B receptor is a G-protein-coupled receptor (GPCR) that exists in two different agonist affinity states. An agonist ligand is expected to be more sensitive towards competition from another agonist, such as endogenous 5-HT, than an antagonist ligand. It is of interest to know whether the intrinsic activity of a PET radioligand for the 5-HT_1B receptor impacts on its ability to detect changes in endogenous synaptic 5-HT density. Three high-affinity ¹¹C-labeled 5-HT_1B PET radioligands with differing intrinsic activity were applied to PET measurements in cynomolgus monkey to evaluate their sensitivity to be displaced within the brain by endogenous 5-HT. For these experiments, fenfluramine was pre-administered at two different doses (1.0 and 5.0 mg/kg, i.v.) to induce synaptic 5-HT release.

Results

A dose-dependent response to fenfluramine was detected for all three radioligands. At the highest dose of fenfluramine (5.0 mg/kg, i.v.), reductions in specific binding in the occipital cortex increased with radioligand agonist efficacy, reaching 61% for [¹¹C]3. The most antagonistic radioligand showed the lowest reduction in specific binding.

Conclusions

Three 5-HT_1B PET radioligands were identified with differing intrinsic activity that could be used in imaging high- and low-affinity states of 5-HT_1B receptors using PET. From this limited study, radioligand sensitivity to endogenous 5-HT appears to depend on agonist efficacy. More extensive studies are required to substantiate this suggestion.

Development of a 18F-labeled PET radioligand for imaging 5-HT1B receptors: [18F]AZ10419096

INTRODUCTION

In the last decade PET has been useful in studying and understanding the 5-HT_1B receptor. [¹¹C]AZ10419369 and [¹¹C]P943 have been applied as radioligands in these studies. Both use carbon-11 (t_1/2 = 20.4 min) as radionuclide, which limits the application to PET centres that have an on-site cyclotron and radiochemistry facilities. In this paper we report the synthesis and initial evaluation of the first fluorine-18 PET radioligand to image 5-HT_1B receptors in brain, [¹⁸F]AZ10419096.

MATERIALS AND METHODS

A boronate-precursor for [¹⁸F]AZ10419096 was synthesized from an intermediate provided by AstraZeneca and was labeled with fluorine 18 using Cu-mediated radio-fluorination. [¹⁸F]AZ10419096 was used in PET baseline and pretreatment measurements in nonhuman primates. PET data were analyzed using SRTM using the cerebellum as reference region. Blood samples for radio-metabolite analysis were collected during PET measurements.

RESULTS

Radio-fluorination gave [¹⁸F]AZ10419096 in sufficient amounts and molar activity and with high radiochemical purity to be applied in PET measurements. In a baseline PET measurement [¹⁸F]AZ10419096 showed a high brain uptake and regional distribution consistent with reported 5-HT_1B receptor densities. In a pretreatment PET measurement, AR-A000002 (2.0 mg/kg) blocked the binding of [¹⁸F]AZ10419096 to 5-HT_1B receptors in occipital cortex by 80%, thereby demonstrating high specific binding.

CONCLUSION

[¹⁸F]AZ10419096 is the first fluorine-18 PET radioligand for imaging 5-HT_1B receptors in vivo with high specific binding and binding potential. [¹⁸F]AZ10419096 is a candidate for further development for use in clinical PET studies.

Synthesis and evaluation of two new candidate high-affinity full agonist PET radioligands for imaging 5-HT1B receptors

INTRODUCTION

The serotonin 1B receptor subtype is of interest in the pathophysiology and treatment of depression, anxiety, and migraine. Over recent years 5-HT_1B receptor binding in human brain has been examined with PET using radioligands that are partial but not full agonists. To explore how the intrinsic activity of a PET radioligand may affect imaging performance, two high-affinity full 5-HT_1B receptor agonists (AZ11136118, 4; and AZ11895987, 5) were selected from a large compound library and radiolabeled for PET examination in non-human primates.

METHODS

[¹¹C]4 was obtained through Pd(0)-mediated insertion of [¹¹C]carbon monoxide between prepared iodoarene and homochiral amine precursors. [¹¹C]5 was obtained through N-¹¹C-methylation of N-desmethyl precursor 6 with [¹¹C]methyl triflate. [¹¹C]4 and [¹¹C]5 were studied with PET in rhesus or cynomolgus monkey. [¹¹C]4 was studied with PET in mice and rats to measure brain uptake and specific binding. Ex-vivo experiments in rats were performed to identify whether there were radiometabolites in brain. Physiochemical parameters for [¹¹C]4 (pKa, logD and conformational energetics) were evaluated.

RESULTS

Both [¹¹C]4 and [¹¹C]5 were successfully produced in high radiochemical purity and in adequate amounts for PET experiments. After intravenous injection of [¹¹C]4, brain radioactivity peaked at a low level (0.2 SUV). Pretreatment with tariquidar, an inhibitor of the brain P-gp efflux transporter, increased brain exposure four-fold whereas pretreatment with a high pharmacological dose of the 5-HT_1B antagonist, AR-A000002, had no effect on the binding. Ex-vivo experiments in rats showed no radiometabolites entering brain. [¹¹C]5 also failed to enter monkey brain under baseline conditions.

CONCLUSIONS

[¹¹C]4 and [¹¹C]5 show too low brain uptake and specific binding to be useful PET radioligands. Low brain uptake is partly ascribed to efflux transporter action as well as unfavorable conformations.

[11C]AZ10419096 - a full antagonist PET radioligand for imaging brain 5-HT1B receptors

INTRODUCTION

The serotonergic system is widely present in all regions of the central nervous system (CNS) and plays a key modulatory role in many of its functions. Positron emission tomography (PET) is used to study several serotonin receptors in CNS in vivo. The G-protein coupled receptor 5-HT_1B is mostly present in the occipital cortex and in midbrain and is linked to several psychiatric disorders. There is evidence that agonist PET radioligands for neuroreceptors are more sensitive to endogenous neurotransmitters than antagonists. Our previously developed 5-HT_1B receptor PET radioligand, [¹¹C]AZ10419369, is now considered a partial agonist. In this work we are aiming to develop a full antagonist PET radioligand for imaging brain 5-HT_1B receptors, and evaluate its sensitivity to increased endogenous serotonin concentration.

MATERIALS

[¹¹C]AZ10419096 was synthesized by rapid methylation of the prepared corresponding N-desmethyl precursor with [¹¹C]methyl triflate. Five PET measurements were performed in cynomolgus monkeys, consisting of two at baseline, one after treatment of a monkey with a 5-HT_1B antagonist, AR-A000002, and two in which fenfluramine was administered during scanning to induce endogenous serotonin release.

RESULTS AND DISCUSSION

[¹¹C]AZ10419096 was synthesized in high yield and purity within 30 min, including purification, formulation and sterile filtration. The baseline PET measurements demonstrated [¹¹C]AZ10419096 to have favorable radioligand characteristics, including high specific binding in brain regions that have high 5-HT_1B density, such as occipital cortex and globus pallidus, as well as subsequent rapid elimination from brain and a minor abundance of lipophilic radiometabolites in plasma. AR-A00002 completely blocked radioligand receptor-specific binding. Fenfluramine produced a distinct displacement of radioligand consistent with an expected increase of synaptic endogenous serotonin concentration.

CONCLUSIONS

[¹¹C]AZ10419096, a full 5-HT_1B antagonist PET radioligand, demonstrates high specific binding in monkey brain that is sensitive to competition from a known 5-HT_1B antagonist as well as to putatively increased endogenous serotonin levels.

Prevalence, age at onset, and risk factors of self-reported asthma among Swedish adolescent elite cross-country skiers

The objective of the study was to compare the prevalence of self-reported physician-diagnosed asthma and age at asthma onset between Swedish adolescent elite skiers and a reference group and to assess risk factors associated with asthma. Postal questionnaires were sent to 253 pupils at the Swedish National Elite Sport Schools for cross-country skiing, biathlon, and ski-orienteering ("skiers") and a random sample of 500 adolescents aged 16-20, matched for sport school municipalities ("reference"). The response rate was 96% among the skiers and 48% in the reference group. The proportion of participants with self-reported physician-diagnosed asthma was higher among skiers than in the reference group (27 vs 19%, P=.046). Female skiers reported a higher prevalence of physician-diagnosed asthma compared to male skiers (34 vs 20%, P=.021). The median age at asthma onset was higher among skiers (12.0 vs 8.0 years; P<.001). Female sex, family history of asthma, nasal allergy, and being a skier were risk factors associated with self-reported physician-diagnosed asthma. Swedish adolescent elite cross-country skiers have a higher asthma prevalence and later age at asthma onset compared to a reference population. Being an adolescent, elite skier is an independent risk factor associated with asthma.

Syndromic surveillance using laboratory test requests: a practical guide informed by experience with two systems

Syndromic surveillance systems can enhance early disease warning, endemic disease monitoring, or help to accumulate proof of disease freedom. In order to provide immediate feedback to achieve these goals, the health data sources scanned should be acquired continuously, in an automated fashion, and should be stored electronically. Recognizing that data from diagnostic test requests often meet these requirements, two systems designed to automatically extract surveillance information from animal laboratory databases have been developed and are described in this paper. These systems are designed to contribute to early disease detection, as well as the timely management of epidemiological information, in a province of Canada and in Sweden, the areas served by the diagnostic laboratories concerned. Classifying in-coming requests into syndromes, the first step, was the most time-consuming and the least portable step between the two systems. The remaining steps were more easily adjusted from one system to implementation in the other. These steps included: retrospective evaluation of data to create baseline profiles following the removal of excessive noise and aberrations; the identification of temporal effects; prospective evaluation of detection algorithms; and finally real-time monitoring and implementation. Building upon the institutions' existing data management software, all steps to use those data for the purposes of syndromic surveillance were set up using open source software; as a result this approach could be readily adopted by other institutions. Relatively straight-forward development and maintenance is expected to lead to the incorporation of these systems into each institution's surveillance processes, becoming an indispensable tool for diagnosticians and epidemiologists, as well as stimulating further technical development of such systems.

Longevity of posterior composite restorations: a systematic review and meta-analysis

The aim of this meta-analysis, based on individual participant data from several studies, was to investigate the influence of patient-, materials-, and tooth-related variables on the survival of posterior resin composite restorations. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a search resulting in 12 longitudinal studies of direct posterior resin composite restorations with at least 5 years' follow-up. Original datasets were still available, including placement/failure/censoring of restorations, restored surfaces, materials used, reasons for clinical failure, and caries-risk status. A database including all restorations was constructed, and a multivariate Cox regression method was used to analyze variables of interest [patient (age; gender; caries-risk status), jaw (upper; lower), number of restored surfaces, resin composite and adhesive materials, and use of glass-ionomer cement as base/liner (present or absent)]. The hazard ratios with respective 95% confidence intervals were determined, and annual failure rates were calculated for subgroups. Of all restorations, 2,816 (2,585 Class II and 231 Class I) were included in the analysis, of which 569 failed during the observation period. Main reasons for failure were caries and fracture. The regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces.

Syndromic surveillance using laboratory test requests: a practical guide informed by experience with two systems

Syndromic surveillance systems can enhance early disease warning, endemic disease monitoring, or help to accumulate proof of disease freedom. In order to provide immediate feedback to achieve these goals, the health data sources scanned should be acquired continuously, in an automated fashion, and should be stored electronically. Recognizing that data from diagnostic test requests often meet these requirements, two systems designed to automatically extract surveillance information from animal laboratory databases have been developed and are described in this paper. These systems are designed to contribute to early disease detection, as well as the timely management of epidemiological information, in a province of Canada and in Sweden, the areas served by the diagnostic laboratories concerned. Classifying in-coming requests into syndromes, the first step, was the most time-consuming and the least portable step between the two systems. The remaining steps were more easily adjusted from one system to implementation in the other. These steps included: retrospective evaluation of data to create baseline profiles following the removal of excessive noise and aberrations; the identification of temporal effects; prospective evaluation of detection algorithms; and finally real-time monitoring and implementation. Building upon the institutions' existing data management software, all steps to use those data for the purposes of syndromic surveillance were set up using open source software; as a result this approach could be readily adopted by other institutions. Relatively straight-forward development and maintenance is expected to lead to the incorporation of these systems into each institution's surveillance processes, becoming an indispensable tool for diagnosticians and epidemiologists, as well as stimulating further technical development of such systems.

Investigations and actions taken during 2011 due to the first finding of Echinococcus multilocularis in Sweden

Echinococcus multilocularis is a parasite that can cause alveolar echinococcosis disease. After the first positive finding of E. multilocularis in Sweden in 2011, a consulting group with representatives from relevant authorities was summoned. In this group, all relevant information was shared, strategies for information dissemination and any actions to be taken due to the finding of E. multilocularis were discussed and decided. The present paper describes the actions taken during 2011 and the results thereof, including surveillance in animals, risk assessment for humans to become infected and recommendations given to the public. Further discussion about whether the parasite was introduced, and if so, how, as well as possible future development of the infection in animals and humans in Sweden and future actions are included.

Response to growth hormone treatment in isolated growth hormone deficiency versus multiple pituitary hormone deficiency

BACKGROUND

Growth hormone (GH) therapy successfully increases height prognosis in children with GH deficiency (GHD); however, adult height data are still limited.

AIM

This study investigated near-adult height (NAH) in patients with idiopathic GHD (i.e. those with a GH peak <10 μg/l with no organic pathology) divided into two groups: isolated GHD and multiple pituitary hormone deficiency (MPHD).

METHODS

All patients were registered in the Pfizer International Growth Study Database (KIGS). Median (10th to 90th percentile) values are given and measurements were expressed as standard deviation scores (SDS). Parental-adjusted height was determined.

RESULTS

GH therapy was started at a median age of 9.2 (range 4.9-12) years in patients with isolated GHD (n = 1,619, 60% males) and at 7.7 (range 2.8-12.2) years in those with MPHD (n = 554, 65% males; p < 0.001) at a median dose of 0.20 mg/kg/week. Height SDS at onset of therapy was -3.1 (range -4.5 to -2.1) and -3.8 (range -5.7 to -2.3), respectively (p < 0.001). The maximum GH peak and insulin-like growth factor I SDS were significantly (p < 0.05) lower in patients with MPHD than in those with isolated GHD. Both groups showed a significant (p < 0.05) increase in height SDS at 1 year that continued until the onset of puberty. Parental-adjusted height at the start of puberty was -0.1 (range -1.6 to 1.1) in patients with isolated GHD and -0.4 (range -1.9 to 1.2) in those with MPHD. Parental-adjusted NAH SDS in patients with isolated GHD was 0.0 (range -1.5 to 1.2) and slightly, but significantly, higher than NAH (-0.3, range -2.1 to 1.2; p < 0.001) in patients with MPHD. In patients with isolated GHD, total change in height SDS while receiving GH therapy was 1.6 (range 0.5-3.2), and the change in height SDS at puberty was 0.1 (range -0.7 to 1). The respective values were 2.6 (range 0.9-4.6) and 0.2 (range -1 to 1.3) in patients with MPHD. Parental-adjusted NAH was slightly lower in girls than in boys with isolated GHD, but no gender difference was observed in patients with MPHD. Multivariate analysis in patients with GHD and MPHD showed that higher birth weight, taller parents, greater height at onset, first-year responsiveness, and predicted height velocity were the most important predictors of NAH.

CONCLUSIONS

89% of patients with isolated GHD and 81% of those with MPHD reached an NAH within their genetic potential while receiving GH therapy. Most of the height gain occurred during prepubertal years.

First detection of Echinococcus multilocularis in Sweden, February to March 2011

Surveillance for the fox tapeworm, Echinococcus multilocularis, has been carried out in Sweden since 2000, with about 300 red foxes analysed annually. We report the first finding of E. multilocularis in Sweden, in a fox shot in December 2010 in the south-west of the country. A second infected fox shot in the same location was detected in March 2011. This paper describes the national monitoring programme and the ongoing work to estimate the prevalence and spread of the infection.

First detection of Echinococcus multilocularis in Sweden, February to March 2011

Surveillance for the fox tapeworm, Echinococcus multilocularis, has been carried out in Sweden since 2000, with about 300 red foxes analysed annually. We report the first finding of E. multilocularis in Sweden, in a fox shot in December 2010 in the south-west of the country. A second infected fox shot in the same location was detected in March 2011. This paper describes the national monitoring programme and the ongoing work to estimate the prevalence and spread of the infection.

Sorption and Diffusion of Radionuclides in Rock Matrix and Natural Fracture Surfaces Studied by Autoradiography

A method based on autoradiography was developed to determine the sorption and diffusion of cesium, strontium, cobalt, nickel, iodine and americium into rock matrix. Samples chosen for this study were filled and unfilled natural fracture surfaces and drill cores having a central drilled hole (”). Rock types were mica gneiss, tonalite and rapakivi granite, which were selected to represent the common rocks and minerals in Finnish bedrock. Distribution coefficients (Ka-values) of cesium and strontium determined for fissure surfaces and drill core cups were of the same order of magnitude. After three months contact time the greatest penetration depth for cesium was 2.5 mm, for a natural fissure surface sample of rapakivi granite. For strontium the penetration depths of 11 mm in three months and 35 mm in twelve months were found for filled natural fissure surface samples of rapakivi granite. The range of Da-values was 1.5 × 10−15 - 3.2 × 10−14 m2/s and 1.4 × 10−14 - 2.1 × 10−13 m2/s for cesium and strontium, resp. For cobalt the Da-values of 5 × 1016 m2/s in tonalite was obtained. In six months the penetration depths of nickel, iodine and americium were too low (< 0.5 mm) to allow calculation of Da.

The Obstructive Lung Disease in Northern Sweden Chronic Obstructive Pulmonary Disease Study: design, the first year participation and mortality

BACKGROUND

Most epidemiological data on chronic obstructive pulmonary disease (COPD) are cross-sectional, and the longitudinal course of disease on population bases is incompletely described.

AIM

To describe an epidemiological study designed to follow the longitudinal course of disease in chronic obstructive lung disease, COPD, including co-morbidity and mortality and further, to evaluate the impact of COPD on quality of life and health economics.

MATERIALS AND METHODS

From the Obstructive Lung Disease in Northern Sweden studies database cohorts I-IV, all subjects with COPD according to the Global Initiative for Chronic Obstructive Lung Disease spirometric criteria, FEV(1)/FVC < 0.70 (n = 993), were identified together with a similar size age- and gender-matched control group. The study population was invited to a yearly examination starting in year 2005. The examinations included structured interview, spirometry with reversibility testing, oxygen saturation and health-related quality of life questionnaires.

RESULTS

On the first year, 83% of the population was examined, and the subjects unable to attend the examination were interviewed by telephone. Altogether, 91% of the original study population participated (95% of all subjects were alive at the end of the first year). Mortality was significantly higher among subjects with COPD, 5.1%, compared with controls, 3.0% (P = 0.018).

CONCLUSION

The study design including cases of COPD representative of COPD by disease severity in the general population and a similar sized control group, together with a high participation rate in the first study year, creates excellent conditions for evaluating the impact of COPD on population bases, and to follow the longitudinal course of disease in COPD.

Concomitant obstructive sleep apnea and chronic obstructive pulmonary disease: study design--the OLIN OSAS-COPD study

BACKGROUND

Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are both common disorders. Concomitant disease, overlap syndrome, is reported to cause a more severe condition.

AIM

To describe a study designed to evaluate the prevalence of overlap syndrome in the general population, and further, to assess the impact of overlap syndrome on cardiovascular morbidity and health-related quality of life. A secondary aim is to evaluate screening oxygen saturation (Sa02) by pulse oxymetry.

MATERIAL AND METHOD

From the last examination of the OLIN-studies (Obstructive Lung Disease in Northern Sweden), cohorts I-IV all subjects with FEV1 < or = 50 percent predicted or Sa02 < or = 93 percent predicted were identified (Phase 1). They are invited to a program including lab tests, spirometry, arterial blood gases, chest x-ray, echocardiography, sleep studies and health-related quality of life (HRQL) questionnaires. In Phase 2, a random sample of subjects reporting snoring as a problem (n = 100) will be invited to a limited program above all including sleep studies and HRQL questionnaires; and in Phase 3, a random sample (n = 100) will be invited to a similar program.

SUMMARY

The collection of data in Phase 1 is in progress and will be completed by the end of year 2007. Phase 2 will start year 2008.

Real-time PCR for Clostridium botulinum type C neurotoxin (BoNTC) gene, also covering a chimeric C/D sequence--application on outbreaks of botulism in poultry

In recent years, botulism type C has become a serious problem in poultry flocks in Sweden. A real-time PCR assay for Clostridium botulinum (C. botulinum) type C neurotoxin (BoNTC) gene was developed as an alternative to the mouse bioassay for detection and identification of C. botulinum type C. The complete method consists of an optimized enrichment protocol followed by automated DNA extraction prior to real-time PCR. The sensitivity of the PCR assay was determined with purified DNA to approximately 50 copies per PCR reaction. The specificity of the PCR assay was evaluated on a panel of about thirty relevant bacteria and on samples of caecum from birds collected in connection with botulism outbreaks on Swedish poultry farms. The PCR assay also covers a previously reported chimeric C/D sequence of the gene. Caecum samples from the outbreaks were positive by real-time PCR. Some of these samples were also examined with a set of conventional PCR methods, to distinguish the gene for the chimeric form from the conserved type C gene. Interestingly, the caecum samples were found to be positive for the chimeric C/D sequence. This is the first study in Europe demonstrating the chimeric C/D sequence. When the toxin gene in two of the samples was sequenced, it was closely identical (99-100%) with several previously reported C/D chimeric sequences. DNA extraction and the real-time PCR assay were both performed in a 96-well format, facilitating for future large-scale detection in outbreak situations and prevalence studies.

Validation of a national disease recording system for dairy cattle against veterinary practice records

In Sweden, morbidity in dairy cattle is monitored through a national disease recording system. This system gives valuable information for research as well as advisory work and genetic evaluation. Our main objective was to evaluate the completeness in the disease recording system. Farm copies of veterinary records (n=851) from 112 herds, from March 2003 to April 2004, were compared with the information registered in the recording system. The evaluation of completeness was performed at two stages: (i) in the raw data transferred from the Swedish Board of Agriculture (SBA) to the Swedish Dairy Association (for records, cases and diagnostic events) and (ii) in the dairy disease database (DDD) at the Swedish Dairy Association (for diagnostic events). The evaluation was stratified by record type: manual and computerized records from state-employed veterinarians and private veterinarians, respectively. The completeness was high both for records (95-100%) and cases (90-99%) except manual records from private veterinarians (76% for records and 74% for cases). The overall completeness for diagnostic events was 75% in the DDD, with significant differences between record types. For all record types other than manual records from private veterinarians, the majority of diagnostic events lost disappeared after registration in the raw data from the SBA. The reasons for loss found suggest that there is potential for improvement. A multilevel logistic regression analysis showed that the completeness of diagnostic events in the DDD depended on region, diagnosis and veterinary employment. The random effect of veterinarian accounted for 35% of the modeled variation. Future studies are needed to assess how the differential misclassification affect estimates based on the data, and how to account for it.

Comparison between dairy cow disease incidence in data registered by farmers and in data from a disease-recording system based on veterinary reporting

Sweden has a national disease-recording system based on veterinary reporting. From this system, all cattle-disease records are transferred to the dairy industry cattle database (DDD) where they are used for several purposes including research and dairy-health statistics. Our objective was to evaluate the completeness of this data source by comparing it with disease data registered by dairy farmers. The proportion of veterinary-treated disease events was estimated, by diagnosis. Disease incidence in the DDD was compared, by diagnosis and age, with disease data registered by the farmers. Comparison was made, by diagnosis, for (i) all disease events and (ii) those reported as veterinary-treated. Disease events, defined as "observed deviations in health, from the normal" were recorded by the farmers during January, April, July and October 2004. For the diagnoses calving problems, peripartum disorders, puerperal paresis and retained placenta, incidence proportions (IP) with 95% confidence intervals (CIs) were estimated. For all other disease problems, incidence rates (IR) were used. In total, 177 farmers reported at least 1 month and 148 reported all 4 months. Fifty-four percent of all disease events in the farmers' data were reported as veterinary-treated. For several of the most common diagnoses, the IRs and IPs for all events were significantly higher in farmers' data than in the DDD. Examples are, in cows: clinical mastitis, cough, gastro-intestinal disorders and lameness in hoof and limb; and in young stock: cough and gastro-intestinal disorders. For veterinary-treated events only, significant differences with higher IR in the farmers' data were found in young stock for sporadic cough and sporadic gastro-intestinal disorders. The diagnosis "other disorders" had significantly more events in the DDD than in farmers' data, i.e. veterinarians tended to choose more unspecific diagnoses than the farmers. This result indicates that the true completeness is likely to be higher than our estimate. We conclude that for the time period studied there was differential under-reporting associated with the diagnosis, the age of the animal and whether the herd was served by a state-employed or private veterinarian.

Microbial aetiology of acute clinical mastitis and agent-specific risk factors

A nation wide study on the microbial aetiology of cases of acute clinical mastitis in Swedish dairy cows was conducted with the aim to investigate changes in the microbial panorama compared to a previous study performed 1994-1995. Another aim was to investigate some agent-specific environmental and individual risk factors. Milk samples were collected from 987 udder quarter cases from 829 cows during six 2-month periods from May 2002 to April 2003, and data on risk factors and demography were collected at sampling by means of a questionnaire. In total, 1056 bacteriological diagnoses were made. The most frequently isolated bacterial species was Staphylococcus aureus constituting 21.3% of the diagnoses, followed by Escherichia coli (15.9%), Streptococcus dysgalactiae (15.6%), Streptococcus uberis (11.1%), coagulase-negative staphylococci (6.2%), Arcanobacterium pyogenes (6.1%) and Klebsiella spp. (4.2%). Samples with no growth or contamination constituted 10.6% and 4.5% of the diagnoses, respectively. A major shift in the panorama of udder pathogens was not observed compared to the survey in 1994-1995. Isolation of Klebsiella spp. was strongly associated with the use of sawdust as bedding material. On the other hand, using sawdust as bedding reduced the risk of isolating S. uberis relative to using straw or peat. The risk of isolating E. coli increased with increasing milk yield and was higher in loose housing systems than in tie stalls. Isolation of S. aureus was associated with tie stalls, and A. pyogenes with low yielding cows and teat lesions. S. dysgalactiae infections were also associated with teat lesions.