Targeting Alzheimer's disease with gene and cell therapies

Alzheimer's disease (AD) causes dementia in both young and old people affecting more than 40 million people worldwide. The two neuropathological hallmarks of the disease, amyloid beta (Aβ) plaques and neurofibrillary tangles consisting of protein tau are considered the major contributors to the disease. However, a more complete picture reveals significant neurodegeneration and decreased cell survival, neuroinflammation, changes in protein and energy homeostasis and alterations in lipid and cholesterol metabolism. In addition, gene and cell therapies for severe neurodegenerative disorders have recently improved technically in terms of safety and efficiency and have translated to the clinic showing encouraging results. Here, we review broadly current data within the field for potential targets that could modify AD through gene and cell therapy strategies. We envision that not only Aβ will be targeted in a disease-modifying treatment strategy but rather that a combination of treatments, possibly at different intervention times may prove beneficial in curing this devastating disease. These include decreased tau pathology, neuronal growth factors to support neurons and modulation of neuroinflammation for an appropriate immune response. Furthermore, cell based therapies may represent potential strategies in the future.

Comparative effects of dexmedetomidine, propofol, sevoflurane, and S-ketamine on regional cerebral glucose metabolism in humans: a positron emission tomography study

INTRODUCTION

The highly selective α₂-agonist dexmedetomidine has become a popular sedative for neurointensive care patients. However, earlier studies have raised concern that dexmedetomidine might reduce cerebral blood flow without a concomitant decrease in metabolism. Here, we compared the effects of dexmedetomidine on the regional cerebral metabolic rate of glucose (CMR_glu) with three commonly used anaesthetic drugs at equi-sedative doses.

METHODS

One hundred and sixty healthy male subjects were randomised to EC₅₀ for verbal command of dexmedetomidine (1.5 ng ml^-1; n=40), propofol (1.7 μg ml^-1; n=40), sevoflurane (0.9% end-tidal; n=40) or S-ketamine (0.75 μg ml^-1; n=20) or placebo (n=20). Anaesthetics were administered using target-controlled infusion or vapouriser with end-tidal monitoring. ¹⁸F-labelled fluorodeoxyglucose was administered 20 min after commencement of anaesthetic administration, and high-resolution positron emission tomography with arterial blood activity samples was used to quantify absolute CMR_glu for whole brain and 15 brain regions.

RESULTS

At the time of [F¹⁸]fluorodeoxyglucose injection, 55% of dexmedetomidine, 45% of propofol, 85% of sevoflurane, 45% of S-ketamine, and 0% of placebo subjects were unresponsive. Whole brain CMR_glu was 63%, 71%, 71%, and 96% of placebo in the dexmedetomidine, propofol, sevoflurane, and S-ketamine groups, respectively (P<0.001 between the groups). The lowest CMR_glu was observed in nearly all brain regions with dexmedetomidine (P<0.05 compared with all other groups). With S-ketamine, CMR_glu did not differ from placebo.

CONCLUSIONS

At equi-sedative doses in humans, potency in reducing CMR_glu was dexmedetomidine>propofol>ketamine=placebo. These findings alleviate concerns for dexmedetomidine-induced vasoconstriction and cerebral ischaemia.

CLINICAL TRIAL REGISTRATION

NCT02624401.

Ventral striatal dopaminergic defect is associated with hallucinations in Parkinson's disease

BACKGROUND AND PURPOSE

Visual hallucinations (VHs) are a common complication of Parkinson's disease (PD). The pathogenesis of VHs in PD is still largely unclear. The aim of this study was to investigate the dopaminergic mechanisms of VHs and specifically whether the degree of striatal dopamine transporter (DAT) function or extrastriatal serotonin transporter (SERT) function can predict the appearance of VHs in patients with PD.

METHODS

Twenty-two PD patients scanned with [¹²³ I]FP-CIT single photon emission computed tomography at an early stage of their disease who later developed VHs were identified and compared with 48 non-hallucinating PD patients. The groups were matched for age, medication, disease duration and motor symptom severity. Clinical follow-up after the scan was a median (range) of 6.9 (3.8-9.6) years. Imaging analyses were performed with both regions-of-interest-based and voxel-based (Statistical Parametric Mapping) methods for the striatal and extrastriatal regions.

RESULTS

The median interval between the scan and the emergence of VHs was 4.8 years. Patients who developed VHs had 18.4% lower DAT binding in the right ventral striatum (P = 0.009), 16.7% lower binding in the left ventral striatum (P = 0.02) and 18.8% lower binding in the right putamen (P = 0.03) compared to patients who did not develop VHs.

CONCLUSIONS

Low striatal DAT function may predispose PD patients to VHs, and the regional distribution of the findings suggests a particular role of the ventral striatum. This is in line with non-PD research that has implicated ventral striatal dysfunction in psychosis.

Heparin-binding protein as a biomarker of acute kidney injury in critical illness

BACKGROUND

There is no biomarker with high sensitivity and specificity for the development of acute kidney injury (AKI) in a mixed intensive care unit (ICU) population. Heparin-binding protein (HBP) is released from granulocytes and causes increased vascular permeability which plays a role in the development of AKI in sepsis and ischemia. The aim of this study was to investigate whether plasma levels of HBP on admission can predict the development of AKI in a mixed ICU population and in the subgroup with sepsis.

METHODS

Longitudinal observational study with plasma HBP levels from 245 patients taken on admission to ICU. Presence and severity of AKI was scored daily for 1 week.

RESULTS

Mean (95% CI) plasma concentrations of log HBP (ng/ml) in the groups developing different stages of AKI were: stage 0 (n = 175), 3.5 (3.4-3.7); stage 1 (n = 33), 3.7 (3.5-4.0), stage 2 (n = 20), 4.4 (3.5-4.8); and stage 3 (n = 17), 4.6 (3.8-5.2). HBP levels were significantly higher in patients developing AKI stage 3 (P < 0.01) compared to AKI stage 0 and 1. The area under the curve (AUC) for HBP to discriminate the group developing AKI stage 2-3 was 0.70 (CI: 0.58-0.82) and in the subgroup with severe sepsis 0.88 (CI: 0.77-0.99).

CONCLUSION

Heparin-binding protein levels on admission to ICU are associated with the development of severe kidney injury. The relationship between HBP and AKI needs to be further validated in larger studies.

iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova

We report the discovery of a multiply imaged, gravitationally lensed type Ia supernova, iPTF16geu (SN 2016geu), at redshift z = 0.409. This phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy. We used high-spatial-resolution observations to resolve four images of the lensed supernova, approximately 0.3 arc seconds from the center of the foreground galaxy. The observations probe a physical scale of ~1 kiloparsec, smaller than is typical in other studies of extragalactic gravitational lensing. The large magnification and symmetric image configuration imply close alignment between the lines of sight to the supernova and to the lens. The relative magnifications of the four images provide evidence for substructures in the lensing galaxy.

Outcome of neoadjuvant therapies for cancer of the oesophagus or gastro-oesophageal junction based on a national data registry

BACKGROUND

Randomized trials have shown that neoadjuvant treatment improves survival in the curative treatment of oesophageal and gastro-oesophageal junction cancer. Results from population-based observational studies are, however, sparse and ambiguous.

METHODS

This prospective population-based cohort study included all patients who had oesophagectomy for cancer in Sweden, excluding clinical T1 N0, recorded in the National Register for Oesophageal and Gastric Cancer, 2006-2014. Patients were stratified into three groups: surgery alone, neoadjuvant chemotherapy and neoadjuvant chemoradiotherapy.

RESULTS

Neoadjuvant treatment was given to 521 patients (51·1 per cent) and 499 (48·9 per cent) received surgery alone. Neoadjuvant chemotherapy increased the risk of postoperative surgical complications compared with surgery alone (adjusted odds ratio 2·01, 95 per cent c.i. 1·24 to 3·25; P = 0·005). Postoperative mortality was significantly increased after neoadjuvant chemoradiotherapy compared with surgery alone (odds ratio 2·37, 1·06 to 5·29; P = 0·035). Survival improved in patients with squamous cell carcinoma after neoadjuvant chemotherapy, whereas after neoadjuvant chemoradiotherapy survival was significantly improved only in the subgroup with the highest performance status and without known co-morbidity. In adenocarcinoma there was a trend towards improved overall survival after neoadjuvant chemotherapy, but neoadjuvant chemoradiotherapy did not offer a survival benefit. Stratified analysis including only patients with adenocarcinoma in the highest performance category without known co-morbidity showed a strong trend towards improved survival after neoadjuvant chemotherapy compared with surgery alone (adjusted hazard ratio 0·47, 0·21 to 1·04; P = 0·061).

CONCLUSION

For patients with squamous cell carcinoma of the oesophagus or gastro-oesophageal junction, neoadjuvant treatments seemed to increase long-term survival, but also the risk of postoperative morbidity and mortality, compared with surgery alone. Neither neoadjuvant treatment option seemed to improve survival significantly among patients with adenocarcinoma, compared with surgery alone.

Lessons Learnt from the Fukushima Accident-A Swedish Medical Preparedness Perspective

The triple disaster in March 2011 tragically and severely affected the Japanese society, in spite of its well-developed infrastructure and good access to resources. A multitude of Japanese and international reports have since described the chain of events and actions taken in connection with the earthquake, the tsunami and the power plant failure in Fukushima. In order to further evaluate Japanese experiences of the disaster, and to bring home 'lessons-learnt' of relevance for continued emergency preparedness planning, a group from the National Board of Health and Welfare and other Swedish agencies performed an observer visit to Japan in 2012. A report from the group was recently published. Its main conclusions, and implications focusing on a strengthened national medical preparedness for radionuclear events in Sweden (and possibly elsewhere), are presented here.

Optimization of ecg gating in quantitative femoral angiography

Purpose: To determine which phase of the heart cycle would yield the highest reproducibility in measuring atherosclerosis-related variables such as arterial lumen volume and edge roughness.

Material and Methods: 35 patients with hypercholesterolemia underwent select‐ ive femoral angiography, repeated four times at 10-min intervals. The angiographies were performed with ECG-gated exposures. In angiographies 1 and 2 the delay from R-wave maximum to each exposure was 0.1 s, in angiographies 3 and 4 the delay was 0.1, 0.3, 0.5 or 0.7 s or the exposures were performed 1/s without ECG gating. Arterial lumen volume and edge roughness were measured in a 20-cm segment of the superficial femoral artery using a computer-based densitometric method. Measurement reproducibility was determined by comparing angiographies 1–2 and angiographies 3–4.

Results: When measuring arterial lumen volume and edge roughness of a 20-cm segment of the femoral artery, reproducibility was not dependent on ECG gating. In measuring single arterial diameters and cross-sectional areas, the reproducibility was better when exposures were made 0.1 s after the R-wave maximum than when using other settings of the ECG gating device or without ECG gating.

Conclusion: The influence of pulsatile flow upon quantitative measurement in femoral angiograms seems to be the smallest possible in early systole, as can be demonstrated when measuring single diameters and cross-sectional areas. In variables based on integration over longer segments, measurement reproducibility seems to be independent of phase.

Reproducibility of Quantitative Arteriographic Assessment of Atherosclerosis in the Femoral Artery

Results from computer-analysed angiograms in the Probucol Quantitative Regression Swedish Trial (PQRST) were analysed to determine the reproducibility of the method and any drift in the analysing system. The precision index (P(μ)) for 2 angiography series, made at 10 min intervals, of the femoral artery in 276 patients was 10.5 for lumen volume and 21.9 for roughness (edge irregularity). No difference in reproducibility was found between patients with and without symptoms of peripheral atherosclerosis or when looking at the reproducibility over years. A drift of 0.67% per year in the radiographic equipment (but not in the analysis system) was found, confirmed by use of phantoms. Computer-based analysis of femoral atherosclerosis is a reliable method for follow-up trials, giving high reproducibility even if the trial spans over several years and involves different centres. The use of phantoms is essential for checking the method over time.

Arterial Segmental Vasoconstriction in Hypercholesterolaemic Patients

Regular, wave-like constriction in medium-sized arteries, arterial segmental vasoconstriction (ASV), has been observed at arteriography and described by many authors. We found ASV in arteriograms of the superficial femoral artery in 13 of 107 hypercholesterolaemic patients, enrolled in the Probucol Quantitative Regression Swedish Trial (PQRST). The arteriograms were digitized and studied with a quantitative computer-assisted technique. The frequency of ASV was higher than has been reported earlier in clinical materials, possibly because of an increased vasoreactivity in hypercholesterolaemia, as recently observed experimentally. The ASV patients were, on average, younger, had lower blood pressure and less atherosclerosis, than the non-ASV patients. ASV was not found in any of the 19 patients in the material who either had symptoms of peripheral vascular disease or arteriographically verified arterial occlusions. No significant correlations with smoking habits or serum cholesterol levels were found. A computer-based index of ASV and measurement of ASV wavelength are discussed.

S, Walldius G. Allergic reactions at repeat femoral angiography with ioxaglate

Purpose: To study the occurrence of allergy-like reactions at angiography, repeated several times, and, secondly, to evaluate the effect of prophylactic treatment in individuals who had earlier experienced such reactions.

Material and Methods: One hundred and fifty-seven patients with hypercholesterolaemia, participating in the Probucol Quantitative Regression Swedish Trial (PQRST), underwent aortofemoral angiography with ioxaglate (Hexabrix) repeated annually for 3 years. Allergic reactions to the contrast medium were recorded. At the following angiographies, all patients who had earlier experienced such reactions were treated prophylactically with steroids and antihistamine.

Results: Allergic reactions were observed in 35 patients. Twelve reacted only year 0, 3 only year 1, 5 only year 2 and 6 only year 3. Eight patients had at least one reaction also when treated prophylactically. It was significantly ( p&lt;0.05) more common to react at year 0 but not at year 1 than to react at year 1 but not at year 0. At years 1, 2 and 3 the frequency of reactions was significantly greater in the group given prophylactic treatment than in the group without any earlier reaction at all: 8/20 versus 3/137, 4/23 versus 6/134, and 6/29 versus 6/128, respectively.

Conclusion: Some individuals had an increased risk of an allergy-like reaction to the contrast agent. Prophylactic treatment reduced the risk of renewed reactions, but not to the same level as for those without earlier reaction. Nevertheless, individuals who have had earlier reactions can be investigated in the future, with prophylactic treatment.

Atherosclerosis-Related Measures in Digitized Femoral Arteriograms

Atherosclerosis is reflected in the arteriogram as narrowing of the arterial lumen and irregularity of the arterial wall. We have quantified these changes in digitized femoral arteriograms from 107 hypercholesterolaemic patients and defined 10 different measures concerning arterial diameter, cross-sectional area, stenosis and edge irregularity. We examined the precision of these measures and the correlations between them. Lumen volume and mean diameter for defined arterial segments had the highest precision and may be useful for follow-up studies. The linear correlation between the mean diameter and the square root of the lumen volume was > 0.99, so these two measures seem to be equivalent for all practical purposes. The measured variables could be separated into 2 groups: the measures concerning arterial diameter and lumen volume and those concerning edge irregularity and localized stenosis. The measures within each group showed strong positive mutual correlations, while the correlations between measures from different groups were negative and small. It was concluded that if the results of one measure from each group, suitably those of lumen volume and edge roughness, are known, the other described measures will add no further information about the atherosclerotic process.

Current and future treatment of amyloid diseases

There are more than 30 human proteins whose aggregation appears to cause degenerative maladies referred to as amyloid diseases or amyloidoses. These disorders are named after the characteristic cross-β-sheet amyloid fibrils that accumulate systemically or are localized to specific organs. In most cases, current treatment is limited to symptomatic approaches and thus disease-modifying therapies are needed. Alzheimer's disease is a neurodegenerative disorder with extracellular amyloid β-peptide (Aβ) fibrils and intracellular tau neurofibrillary tangles as pathological hallmarks. Numerous clinical trials have been conducted with passive and active immunotherapy, and small molecules to inhibit Aβ formation and aggregation or to enhance Aβ clearance; so far such clinical trials have been unsuccessful. Novel strategies are therefore required and here we will discuss the possibility of utilizing the chaperone BRICHOS to prevent Aβ aggregation and toxicity. Type 2 diabetes mellitus is symptomatically treated with insulin. However, the underlying pathology is linked to the aggregation and progressive accumulation of islet amyloid polypeptide as fibrils and oligomers, which are cytotoxic. Several compounds have been shown to inhibit islet amyloid aggregation and cytotoxicity in vitro. Future animal studies and clinical trials have to be conducted to determine their efficacy in vivo. The transthyretin (TTR) amyloidoses are a group of systemic degenerative diseases compromising multiple organ systems, caused by TTR aggregation. Liver transplantation decreases the generation of misfolded TTR and improves the quality of life for a subgroup of this patient population. Compounds that stabilize the natively folded, nonamyloidogenic, tetrameric conformation of TTR have been developed and the drug tafamidis is available as a promising treatment.

Transmissible amyloid

There are around 30 human diseases associated with protein misfolding and amyloid formation, each one caused by a certain protein or peptide. Many of these diseases are lethal and together they pose an enormous burden to society. The prion protein has attracted particular interest as being shown to be the pathogenic agent in transmissible diseases such as kuru, Creutzfeldt-Jakob disease and bovine spongiform encephalopathy. Whether similar transmission could occur also in other amyloidoses such as Alzheimer's disease, Parkinson's disease and serum amyloid A amyloidosis is a matter of intense research and debate. Furthermore, it has been suggested that novel biomaterials such as artificial spider silk are potentially amyloidogenic. Here, we provide a brief introduction to amyloid, prions and other proteins involved in amyloid disease and review recent evidence for their potential transmission. We discuss the similarities and differences between amyloid and silk, as well as the potential hazards associated with protein-based biomaterials.