Radiosynthesis and Early Evaluation of a Positron Emission Tomography Imaging Probe [18F]AGAL Targeting Alpha-Galactosidase A Enzyme for Fabry Disease

Success of gene therapy relies on the durable expression and activity of transgene in target tissues. In vivo molecular imaging approaches using positron emission tomography (PET) can non-invasively measure magnitude, location, and durability of transgene expression via direct transgene or indirect reporter gene imaging in target tissues, providing the most proximal PK/PD biomarker for gene therapy trials. Herein, we report the radiosynthesis of a novel PET tracer [18F]AGAL, targeting alpha galactosidase A (α-GAL), a lysosomal enzyme deficient in Fabry disease, and evaluation of its selectivity, specificity, and pharmacokinetic properties in vitro. [18F]AGAL was synthesized via a Cu-catalyzed click reaction between fluorinated pentyne and an aziridine-based galactopyranose precursor with a high yield of 110 mCi, high radiochemical purity of >97% and molar activity of 6 Ci/µmol. The fluorinated AGAL probe showed high α-GAL affinity with IC50 of 30 nM, high pharmacological selectivity (≥50% inhibition on >160 proteins), and suitable pharmacokinetic properties (moderate to low clearance and stability in plasma across species). In vivo [18F]AGAL PET imaging in mice showed high uptake in peripheral organs with rapid renal clearance. These promising results encourage further development of this PET tracer for in vivo imaging of α-GAL expression in target tissues affected by Fabry disease.

3D ultrasound coronarography: first proof of concept study on isolated beating rat hearts

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Bettencourt Foundation

Background/Introduction

We demonstrated recently that Ultrafast ultrasound Doppler imaging can image the intramyocardial coronary circulation in beating hearts of large animals and patients [1]. Yet, ultrasound spatial resolution remains limited by wave physics and coronaries smaller than ∼100 µm could not be imaged. Ultrasound Localization Microscopy (ULM) [2] was recently introduced to tackle this issue and exploit the micrometric localization of microbubble contrast agents at ultrafast frame rate in order to image blood flows in micrometer vessels.

Purpose

The objective of this work was to demonstrate that 3D ultrafast ultrasound with contrast agents can provide the full 3D mapping of the coronary microcirculation with quantitative flow velocity on a beating rat heart.

Methods

Acquisitions were performed on ex vivo rat hearts (n = 5) with retrograde perfusion (Langendorff

model). A flow of a Krebs–Henseleit solution mixed with a diluted microbubbles solution (0.22%) was perfused at controlled pressure into the coronary arteries (between 5 and 15 mL/min). We used a 32 × 32 elements, 8-MHz matrix-array ultrasound transducer connected to a 1024-channel programmable ultrasound scanner. An ultrafast Doppler imaging sequence consisting of 9 plane waves was transmitted at a PRF of 20 kHz during 270 ms and repeated 40 times. After beamforming and SVD clutter filtering, the microbubbles were localized and tracked in 3D. Flow velocity were mapped at baseline and after infusion of Adenosine (10e-5 µMol) at constant coronary perfusion pressure (120 mm Hg). Eventually, the hearts were fixed using formaldehyde perfusion and imaged by µCT after injection of radio opaque agent.

Results

We successfully imaged the coronary blood flows of entire rat hearts. It revealed the entire vasculature from large main coronaries arteries (cross section up to 1 mm) to small arterioles (smaller than 40 µm). Coronary flow velocities ranged from [1 – 50] cm/s depending on the arteries diameter. Velocity estimates were validated in vitro in tubes of Ø0.58mm and were in good agreement with theoretical values of a Poiseuille’s flow (relative ratio of 10% for maximum velocities). After Adenosine infusion, perfusion flow rates increased 102% ± 50% (p < 0.05) on average. Eventually, anatomy revealed by 3D ultrasound coronarography was in accordance with the anatomy revealed by the µCT.

Conclusion(s)

We demonstrated the feasibility of 3D ultrasound coronarography on isolated beating rat hearts. This technique has the potential to become a novel imaging tool to investigate the coronary micro-circulation and quantify non-invasively the Coronary Flow Reserve (CFR).

Abstract Figure. Ultrasound coronarography

[Neuromyelitis optica spectrum disorders: profile of a cohort according to the 2015 diagnostic criteria]

INTRODUCTION

The new 2015 criteria for neuromyelitis optica spectrum disorders (NMOSD) have been recently incorporated in the study of different international cohorts.

AIM

To describe clinical-radiological characteristics and prognostic factors in patients with NMOSD according to the 2015 criteria.

PATIENTS AND METHODS

Retrospective analysis of 36 patients diagnosed with NMOSD according to serologic AQP4 status (positive, negative, unknown and negative + unknown). Clinical and radiological characteristics were compared and possible disability prognostic factors were evaluated.

RESULTS

AQP4 were positive in 7 patients, negative in 12 and unknown in 17. Age of presentation was 36.6 ± 16 years, with higher female proportion (4:1). Mean disease duration was 7.4 ± 7.6 years. Most frequent presenting symptoms were acute myelitis (61%), optic neuritis (33%) and area postrema syndrome (11%). Most frequent MRI lesion was longitudinally extensive transverse myelitis (75%). All patients received acute treatment during attacks, and preventive treatment was used in 81% (azathioprine and rituximab mostly prescribed). Median EDSS was 2.0 at the end of follow-up. No differences were observed in any of the variables comparing serologic status. Age of first attack was prognostic, with direct correlation with EDSS. First attack in < 30 years was protective, meanwhile > 50 years old patients had increased risk of disability.

CONCLUSIONS

The 2015 criteria allow the description and classification of NMOSD patients within different cohorts. Age of first attack seems to be a prognostic factor for developing disability.

Elevated expression levels of lysyl oxidases protect against aortic aneurysm progression in Marfan syndrome

Patients with Marfan syndrome (MFS) are at high risk of life-threatening aortic dissections. The condition is caused by mutations in the gene encoding fibrillin-1, an essential component in the formation of elastic fibers. While experimental findings in animal models of the disease have shown the involvement of transforming growth factor-β (TGF-β)- and angiotensin II-dependent pathways, alterations in the vascular extracellular matrix (ECM) may also play a role in the onset and progression of the aortic disease. Lysyl oxidases (LOX) are extracellular enzymes, which initiates the formation of covalent cross-linking of collagens and elastin, thereby contributing to the maturation of the ECM. Here we have explored the role of LOX in the formation of aortic aneurysms in MFS. We show that aortic tissue from MFS patients and MFS mouse model (Fbn1(C1039G/+)) displayed enhanced expression of the members of the LOX family, LOX and LOX-like 1 (LOXL1), and this is associated with the formation of mature collagen fibers. Administration of a LOX inhibitor for 8weeks blocked collagen accumulation and aggravated elastic fiber impairment, and these effects correlated with the induction of a strong and rapidly progressing aortic dilatation, and with premature death in the more severe MFS mouse model, Fbn1(mgR/mgR), without any significant effect on wild type animals. This detrimental effect occurred preferentially in the ascending portion of the aorta, with little or no involvement of the aortic root, and was associated to an overactivation of both canonical and non-canonical TGF-β signaling pathways. The blockade of angiotensin II type I receptor with losartan restored TGF-β signaling activation, normalized elastic fiber impairment and prevented the aortic dilatation induced by LOX inhibition in Fbn1(C1039G/+) mice. Our data indicate that LOX enzymes and LOX-mediated collagen accumulation play a critical protective role in aneurysm formation in MFS.

Validity and reliability of the T-Scan(®) III for measuring force under laboratory conditions

Although measuring bite force is an important indicator of the health of the masticatory system, few commercially available transducers have been validated for routine clinical use. T-Scan(®) III Occlusal Analysis System allows to record the bite force distribution, indicating its relative intensity and occlusal timing. Nevertheless, even fewer studies have evaluated the validity and reliability of the latest generation of the T-Scan(®) occlusal analysis system. To determine the validity and reliability of the T-Scan(®) III system when measuring total absolute bite force under laboratory conditions. Known forces were applied to 18 T-Scan(®) III sensors, which were classified into two groups differentiated by their production series. Both Lin's concordance correlation coefficient (CCC) and the intra-class correlation coefficient (ICC) were used to assess the system's reliability and validity. Considering all the sensors studied, a substantial level (Lin's CCC 0·969) and a very good level of reliability (CCI 0·994) were obtained. When evaluating the validity of the system, a poor (Lin's CCC 0·530) and moderate (ICC 0·693) agreement were also obtained. The main factor that negatively influenced the validity of the T-Scan(®) III under these study conditions was the significant difference in the behaviour of the two sensor groups. The T-Scan(®) III showed a high degree of reliability when used to perform consecutive measurements. However, the system showed an insufficient degree of validity for measuring absolute force when estimating total occlusal force under laboratory conditions.

[Neuraxial analgesia during labor in a patient with Arnold-Chiari type I malformation and syringomyelia]

Chiari type I malformation is a caudal displacement of the cerebellum with tonsillar herniation through the foramen magnum, frequently associated with syringomyelia, a syndrome characterized by cyst-like cavities in the spinal cord; each of the conditions leads to characteristic neurologic abnormalities. Pregnant patients with these types of malformation are considered to have an increased risk of brainstem compression and/or progression of the disease during labor. We present the case of a patient in labor with a diagnosis of syringomyelia associated with Chiari type I malformation and describe the anesthetic management. The patient revealed during labor that she had syringomyelia associated with Chiari type I malformation, after having made no mention of it in previous history taking. Finally, we review the pathology observed in these patients.

Reversible nitrous oxide myelopathy and a polymorphism in the gene encoding 5,10-methylenetetrahydrofolate reductase

We present a case of a patient who received nitrous oxide on two occasions within a period of 8 weeks and who subsequently developed a diffuse myelopathy, characterized by upper extremity paresis, lower extremity paraplegia and neurogenic bladder. Laboratory testing revealed hyperhomocysteinaemia and low levels of vitamin B(12). Because of this uncommon clinical presentation, we analysed the patient's DNA, and found a polymorphism in the MTHFR gene that is associated with the thermolabile isoform of the 5,10-methylenetetrahydrofolate reductase enzyme, which explained the myelopathy experienced by the patient after being exposed to nitrous oxide. Soon after initiating supplementary therapy with folic acid and vitamin B(12), the neurological symptoms subsided.

Seasonal variation in prevalence of antibody to hantaviruses in rodents from southern Argentina

We conducted a small mammal trapping study to investigate temporal variation in prevalence of infection in hantavirus reservoir populations in the Patagonian Andes mountain range, Rio Negro province, Argentina. Rodent blood samples collected in natural and periurban habitats and at the home of an hantavirus pulmonary syndrome (HPS) case patient were analysed by enzyme-linked immunosorbent assay. Organ tissue samples were tested by polymerase chain reaction (PCR) and nucleotide sequence analysis. Eight species of 1032 rodents were captured in 15 551 trap nights, giving an overall trap success of 6.6%. Hantavirus antibody was detected in 30 of 555 Oligoryzomys longicaudatus (reservoir of Andes virus), three of 411 Abrothrix longipilis, and one of 10 Loxodontomys micropus. Antibody prevalences in O. longicaudatus were 13.7% in spring 1996, 59.3% in summer 1996, 2.1% in autumn 1997, 12.4% in winter 1997 and 3.1% in spring 1997. A much higher antibody prevalence (33%) was found during trapping around the residence of an HPS case patient. Higher prevalences were found in older male O. longicaudatus. There was no apparent correlation of antibody prevalence with rodent population density, or of rodent population density or antibody prevalence with numbers of human cases. For an HPS case that occurred in our study area in 1997, we identified the probable rodent reservoir and likely site of exposure by matching the genetic sequences of virus obtained from a rodent and the HPS case patient.

[Cervical curvature. A cephalometric study in position of clinical rest]

BACKGROUND

Alterations in the head position and in cervical curvature are associated with mandibular dysfunction, an increased vertical occlusal dimension, upper airways obstruction and bad postural behaviors at work among other conditions.

AIM

To perform a cephalometric analysis in young adults.

SUBJECTS AND METHODS

Lateral cervical X-ray examinations were performed in 46 university students (26 female) aged 19 years old as a mean, Cephalometric landmarks and planes reported by Sollow & Tallgren, determined by investigators, were used for radiographic analysis.

RESULTS

The combined error of the method did not exceed 0.9 degree for any studied variable. Mean craniocervical angulations were 102 degrees for OPT-SNL, 109 degrees for CVT-SNL, 94.8 degrees for cranium-C2 and 105 for SN-vertical. There were significant sex differences in craniocervical angulations and these were abnormal in two thirds of subjects studies. The Forward Head Position is characterized by a cervical compensation with head inclination. This abnormal postural position showed a dolichofacial growth and an alteration of hyoid angle.

CONCLUSIONS

The craniocervical position appeared to be related to a vertical craniofacial growth pattern.

[Anatomo-radiological study of the cranio-cervical region in 60 students from Universidad de la Frontera, Chile]

BACKGROUND

Twenty to thirty percent of the population has craniomandibular anomalies, that are closely related to craniocervical disorders.

AIM

To evaluate the craniocervical region from a radiological point of view in healthy young adults.

SUBJECTS AND METHODS

A lateral head and neck radiological study, using the technique described by Rocabado, was done to 60 Chilean young adults, aged 19 to 24 years old.

RESULTS

The cervical curvature was altered in 70% of subjects (kyphosis in 35%, straightening in 33.3% and lordosis in 1.7%). Sixty eight percent had alteration of the hyoid triangle (in the plane in 31.7% and inverted in 37%). The distance between CO and C1 was altered in 48% (less than 4 mm in 15% and more than 9 mm in 33%). An altered posteroinferior angle was observed in 40% (less than 96 degrees in 30% and over 106 degrees in 10%).

CONCLUSION

A high percentage of alterations of the craniocervical region was detected in healthy adults.

The effects of contextual cues on making occupational and gender categorizations

We report one study investigating how persons are categorized when the targets are presented with contextual cues. Using photos of either persons in occupational clothing and in occupational contexts or photos of college students and without distracting stimuli, the response times to verify various group memberships were tested, with the underlying interest of determining how persons are perceived when the persons are clearly members of multiple categories. Consistent with past research, when using rather simplistic photos, women were categorized as women faster than men were categorized as men. With occupational photos, however, women were not categorized as women faster than men were as men, nor were men categorized by occupation faster than were women, contrary to predictions derived from the 'white male default' (Zárate & Smith, 1990). Rather, for female stereotypic occupations, female targets were classified by occupation faster than were male stereotypic occupations, male targets were classified by occupation faster than were female targets. Across all comparisons, subjects categorized same-sex targets faster than other sex targets. Results are discussed for their implications for various person perception models.

Natural Tritium Measurements by Ethane Counting

A method is described for the synthesis of ethane from hydrogen that is at present used for the counting of low-level tritium activity at the La Jolla tritium laboratory. The reaction procedure is simple and involves the mixing of the hydrogen with acetylene over a colloidal palladium catalyst. Counting characteristics of ethane are found to be ideal. With a 1-liter counter filled to three atmospheres of ethane, only a tenfold tritium enrichment is necessary in order to obtain a sensitivity of 0.32 counts per minute per tritium unit.