The effect of entacapone (OR-611) on brain [18F]-6-L-fluorodopa metabolism: implications for levodopa therapy of Parkinson's disease

We used PET and [18F]-6-L-fluorodopa ([18F]dopa) to measure the effect of a peripheral COMT inhibitor, entacapone, on the extracerebral metabolism and subsequent striatal uptake of [18F]dopa. Four parkinsonian patients and six age-matched normal controls were each scanned twice, once after carbidopa (150 mg) plus placebo and once after carbidopa (150 mg) plus entacapone (400 mg or 800 mg). Without entacapone premedication, by 90 minutes from injection, only 22% of the [18F] signal in plasma represented unmetabolized [18F]dopa (the balance being 3-O-methyl[18F]dopa). After entacapone medication, this fraction increased to 56% of the [18F] signal (p < 0.0001). We did not find any significant differences between the changes observed in patients versus controls or between those subjects who received 400 mg entacapone versus 800 mg in either this or any of the other reported measures. PET image contrast increased in all cases, reflecting an increase in the specific striatal signal ([striatum-occipital]:occipital ratio increased 38% [p < 0.0001]). Entacapone did not alter the rate of striatal uptake and decarboxylation of [18F]dopa as estimated using a graphic approach with metabolite-corrected plasma as input function to calculate the influx constant, Ki(p) (p = NS). This confirms that such an analytic approach adequately corrects for the effect of extracerebral [18F]dopa methylation. In contrast, the influx constant Ki(o) (calculated using occipital counts as the input function) increased 45% after entacapone (p < 0.0001). This demonstrates the sensitivity of this analytic approach to the presence of peripheral 3-O-methyl[18F]dopa and provides an estimate of the percentage increase in brain free [18F]dopa resulting from entacapone premedication.

Cake Shrinkage During Freeze Drying: A Combined Experimental and Theoretical Study

The aim of this study is to investigate, by experimental studies and theoretical analysis, the phenomenon of cake shrinkage during the lyophilization process and to investigate the effect of shelf temperature during primary drying and secondary drying on the degree of cake shrinkage. Freeze-drying experiments were performed using 5% w/v sucrose where the drying protocols were altered in order to produce differing product temperature profiles. Resistance data during freeze drying were evaluated by the Manometric Temperature Measurement (MTM) method. Theoretical simulation of the freeze-drying process was performed using the Passage Freeze-Drying software. The difference between the glass transition temperature and the product temperature (Tg-T) obtained from the theoretical analysis was calculated and used for correlation with experimental shrinkage data. The Brunauer, Emmeth, Teller (BET) Specific Surface Area (SSA) Analysis was used as a method to quantify the degree of shrinkage. Samples were also analyzed for pore volume by mercury porosimetry. The SSA analysis on the freeze-dried samples showed an increase in SSA when samples were freeze dried at a lower shelf temperature during primary drying and at a slower ramp rate during secondary drying. The trend in surface area values was consistent with that obtained for pore size values. However, differences obtained among the various samples are small and cake diameter measurements showed that there was approximately 17% shrinkage even in the sample freeze dried at temperatures well below the Tg' and Tg. Variations in process and product temperature only accounted for an additional 2%-3% shrinkage. Resistance data obtained at various primary drying shelf temperatures showed a good correlation with surface area. The Tg-T behavior of the freeze-dried samples showed that a slow ramp rate of 0.1 degrees C/min during secondary drying maintains a product well below the Tg at all times and a higher ramp rate gives negative values of Tg-T. The obtained data suggest that conditions of secondary drying do impact shrinkage, and it is important to maintain a sample well below the collapse temperature during primary drying and below the Tg at all times during secondary drying; however, drying conditions are a second order effect. It seems that, in the case of a sample like sucrose, nearly 17% shrinkage will occur no matter what the product temperature history.

NMDA receptor binding in focal epilepsies

OBJECTIVE

To demonstrate altered N-methyl-d-aspartate (NMDA) receptor availability in patients with focal epilepsies using positron emission tomography (PET) and [(18)F]GE-179, a ligand that selectively binds to the open NMDA receptor ion channel, which is thought to be overactive in epilepsy.

METHODS

Eleven patients (median age 33 years, 6 males) with known frequent interictal epileptiform discharges had an [(18)F]GE-179 PET scan, in a cross-sectional study. MRI showed a focal lesion but discordant EEG changes in two, was non-localising with multifocal EEG abnormalities in two, and was normal in the remaining seven patients who all had multifocal EEG changes. Individual patient [(18)F]GE-179 volume-of-distribution (VT) images were compared between individual patients and a group of 10 healthy controls (47 years, 7 males) using Statistical Parametric Mapping.

RESULTS

Individual analyses revealed a single cluster of focal VT increase in four patients; one with a single and one with multifocal MRI lesions, and two with normal MRIs. Post hoc analysis revealed that, relative to controls, patients not taking antidepressants had globally increased [(18)F]GE-179 VT (+28%; p<0.002), and the three patients taking an antidepressant drug had globally reduced [(18)F]GE-179 VT (-29%; p<0.002). There were no focal abnormalities common to the epilepsy group.

CONCLUSIONS

In patients with focal epilepsies, we detected primarily global increases of [(18)F]GE-179 VT consistent with increased NMDA channel activation, but reduced availability in those taking antidepressant drugs, consistent with a possible mode of action of this class of drugs. [(18)F]GE-179 PET showed focal accentuations of NMDA binding in 4 out of 11 patients, with difficult to localise and treat focal epilepsy.

Surgical treatment of transcatheter aortic valve infective endocarditis

There is growing interest in infections occurring after transcatheter aortic valve implantation (TAVI). The incidence, and clinical and anatomical features suggest many similarities with prosthetic valve endocarditis. The survival of patients with an infected TAVI prosthesis is generally poor; however, only a minority of them (10%) have undergone treatment with surgical explantation of the infected prosthesis. A literature search was performed using online databases. Papers reporting surgical treatment of TAVI prosthesis infections were retrieved, focusing on pre- and intraoperative characteristics and early outcome. Thirty-seven papers ultimately provided information on 107 patients. Their mean ± standard deviation (SD) age was 76 ± 8 years and 72% were male. The mean ± SD time interval between the TAVI procedure and reoperation was 10 ± 10 months. Annular abscess formation was described in 34% of cases and mitral valve involvement in 31%. All patients underwent TAVI prosthesis explantation and surgical aortic valve replacement; concomitant mitral valve replacement was necessary in 22% of cases. Postoperative in-hospital mortality was 28%. Surgical explantation of infected TAVI prostheses was associated with a high postoperative mortality, although these initial experiences included elderly and high-risk patients. Considering the expansion of TAVI procedures towards younger and lower-risk patients, surgical treatment of TAVI endocarditis may represent the best option for a life-saving procedure.

Two routes to [11C-carbonyl]organo-isocyanates utilizing [11C]phosgene ([11C]organo-isocyanates from [11C]phosgene)

Two generic radiosynthetic routes for the preparation of [11C-carbonyl]isocyanates have been developed. Reaction of N-organo-sulfinylamines; RNSO, (R = Me, Et, allyl, cyclohexyl and phenyl) with [11C]phosgene gave the corresponding [11C-carbonyl]isocyanates in good radiochemical yield (53-68%) from [11C]phosgene (decay corrected) in ca 16 min from EOB. Alternatively, the reaction of [11C]phosgene with N,N'-organo-ureas; (RNH)(2)CO, (R = Me, Et, Pr and phenyl) also gave the corresponding [11C-carbonyl]isocyanates in moderate radiochemical yield (9-37%) from [11C]phosgene (decay corrected) in ca 16 min from EOB. For identification, the [11C-carbonyl]organo-isocyanates were derivatized with 1-(2-methoxyphenyl)piperazine in situ to [11C-carbonyl]carboxamides and the position of radiolabelling in the carbonyl group confirmed by [11/13C]co-labeling and subsequent carbon-13 NMR spectroscopy.

High non-specific binding of the β1-selective radioligand 2-125I-ICI-H

Aim: As results of cardiac biopsies suggest, myocardial β1-adrenoceptor density is reduced in patients with chronic heart failure. However, changes in cardiac β2-adrenoceptors vary. With suitable radiopharmaceuticals single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer the opportunity to assess β-adrenoceptors non-invasively. Among the novel racemic analogues of the established β1-selective adrenoceptor antagonist ICI 89.406 the iodinated 2-I-ICI-H showed high affinity and selectivity to β1-adrenoceptors in murine ventricular membranes. The aim of this study was its evaluation as a putative sub-type selective β1-adrenergic radioligand in cardiac imaging. Methods: Competition studies in vitro and in vivo were used to investigate the kinetics of 2-I-ICI-H binding to cardiac β-adrenoceptors in mice and rats. In addition, the radiosynthesis of 2-125I-ICI-H from the silylated precursor 2-SiMe3-ICI-H was established. The specific activity was 80 GBq/µmol, the radiochemical yield ranged from 70 to 80%.

Results: The unlabelled compound 2-I-ICI-H showed high β1-selectivity and -affinity in the in vitro competition studies. In vivo biodistribution studies apparently showed low affinity to cardiac β-adrenoceptors. The radiolabelled counterpart 2-125I-ICI-H showed a high degree of non-specific binding in vitro and no specific binding to cardiac β1-adrenoceptors in vivo. Conclusion: Because of its high non-specific binding 2-125I-ICI-H is no suitable radiotracer for imaging in vivo.

Diabetes management during cardiac surgery in the UK: A survey

AIM

To determine current practice regarding the diabetes management of people undergoing cardiac surgery in the UK.

METHODS

We conducted an online survey of UK cardiothoracic surgeons. All cardiothoracic surgeons listed in the Society of Cardiothoracic Surgery membership directory were invited to participate. The survey, compiled using SurveyMonkey software, comprised 15 closed and open-ended questions about the management of people with diabetes pre- and peri-operatively.

RESULTS

Sixty-two cardiothoracic surgeons from all 33 UK cardiac centres completed the survey. Of these, 44% responded that they routinely measure HbA_1c preoperatively for all patients, 19% had an HbA_1c threshold above which they would not operate and 21% currently undertake a point-of-care HbA_1c measurement during the cardiothoracic outpatient visit. A total of 74% of respondents reported that it was 'easy' or 'very easy' to obtain a diabetes team review; diabetes nurse specialists were the members of the diabetes team working most closely with cardiac surgeons. Up to a third of the surgeons did not provide physical activity recommendations prior to admission and over 80% did not have a different preoperative or surgical diabetes protocol. Inconsistency in the responses within centres suggests that differences in practice may depend on individual surgeons rather than local policy.

CONCLUSIONS

The study demonstrates there is only limited peri-operative management of diabetes in people undergoing cardiac surgery in the UK. There is an opportunity for greater involvement of the diabetes specialist team both before and during admission for surgery to improve outcomes. (Trial registration: ISRCTN10170306).

Targeted activation of human ether-à-go-go-related gene channels rescues electrical instability induced by the R56Q+/- long QT syndrome variant

AIMS

Long QT syndrome type 2 (LQTS2) is associated with inherited variants in the cardiac human ether-à-go-go-related gene (hERG) K+ channel. However, the pathogenicity of hERG channel gene variants is often uncertain. Using CRISPR-Cas9 gene-edited hiPSC-derived cardiomyocytes (hiPSC-CMs), we investigated the pathogenic mechanism underlying the LQTS-associated hERG R56Q variant and its phenotypic rescue by using the Type 1 hERG activator, RPR260243.

METHODS AND RESULTS

The above approaches enable characterization of the unclear causative mechanism of arrhythmia in the R56Q variant (an N-terminal PAS domain mutation that primarily accelerates channel deactivation) and translational investigation of the potential for targeted pharmacologic manipulation of hERG deactivation. Using perforated patch clamp electrophysiology of single hiPSC-CMs, programmed electrical stimulation showed that the hERG R56Q variant does not significantly alter the mean action potential duration (APD90). However, the R56Q variant increases the beat-to-beat variability in APD90 during pacing at constant cycle lengths, enhances the variance of APD90 during rate transitions, and increases the incidence of 2:1 block. During paired S1-S2 stimulations measuring electrical restitution properties, the R56Q variant was also found to increase the variability in rise time and duration of the response to premature stimulations. Application of the hERG channel activator, RPR260243, reduces the APD variance in hERG R56Q hiPSC-CMs, reduces the variability in responses to premature stimulations, and increases the post-repolarization refractoriness.

CONCLUSION

Based on our findings, we propose that the hERG R56Q variant leads to heterogeneous APD dynamics, which could result in spatial dispersion of repolarization and increased risk for re-entry without significantly affecting the average APD90. Furthermore, our data highlight the antiarrhythmic potential of targeted slowing of hERG deactivation gating, which we demonstrate increases protection against premature action potentials and reduces electrical heterogeneity in hiPSC-CMs.

A Cross-Sectional Study of Sex, Race, and Ethnic Representation in Burn Registered Clinical Trials

PURPOSE

The demographic proportions of plastic surgery trials approximating real-world disease have not well been studied. Judicious trial representation is essential in evaluation of treatments across diverse patient populations. Herein, we investigate sex, racial, and ethnic disparities in patient enrollment across burn trials.

METHODS

Cross-sectional analysis of participants enrolled in high-quality, with reduced risk of bias, randomized controlled trials (RCT) on burns registered on clinicaltrials.gov under the query "burn." Completed RCTs reporting at least two demographic groups, employing double masking or greater, and with results accessible through the registry or publications were included. Trial characteristics (sponsor country, site location, initiation year, study phase, masking) and demographic data (sex, race, ethnicity per US reporting guidelines) were collected. The Global Burden of Disease database provided sex-based burn disease burdens. The primary outcome was the population-to-prevalence ratio of enrolled female participants. Secondary outcomes included representation of racial and ethnic populations as related to study blinding, phase, and study/sponsor locations.

RESULTS

Of 546 records, 39 trials met the inclusion criteria (2919 participants). All trials reported sex demographics, with females comprising 37.02% of all participants (PPR = 0.71, 95% CI [0.59, 0.82], likely indicating underrepresentation against their empiric disease burden). Only 7 and 9 trials reported ethnicity and race, respectively, although not comprehensively. Among trials reporting race or ethnicity, Caucasians and Black persons comprised 57.52% and 21.80% of participants, respectively, while only 9.80% had Hispanic/Latino ethnicity. Severe underreporting of race and ethnicity precluded much of secondary significance testing across study variables.

CONCLUSIONS

Females are likely underrepresented in high-quality, US-registered burn trials, unreflective of their real-world disease burden. Further, severe underreporting of race and ethnicity was noted. Future trials should enroll diverse demographics and equitable populations for promotion of study generalizability.

[High non-specific binding of the beta(1) -selective radioligand 2-(125)I-ICI-H]

AIM

As results of cardiac biopsies suggest, myocardial beta(1) -adrenoceptor density is reduced in patients with chronic heart failure. However, changes in cardiac beta(2)-adrenoceptors vary. With suitable radiopharmaceuticals single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer the opportunity to assess beta-adrenoceptors non-invasively. Among the novel racemic analogues of the established beta(1)-selective adrenoceptor antagonist ICI 89.406 the iodinated 2-I-ICI-H showed high affinity and selectivity to beta(1)-adrenoceptors in murine ventricular membranes. The aim of this study was its evaluation as a putative sub-type selective beta(1)-adrenergic radioligand in cardiac imaging.

METHODS

Competition studies in vitro and in vivo were used to investigate the kinetics of 2-I-ICI-H binding to cardiac beta-adrenoceptors in mice and rats. In addition, the radiosynthesis of 2-(125)I-ICI-H from the silylated precursor 2-SiMe(3)-ICI-H was established. The specific activity was 80 GBq/ micro mol, the radiochemical yield ranged from 70 to 80%.

RESULTS

The unlabelled compound 2-I-ICI-H showed high beta(1)-selectivity and -affinity in the in vitro competition studies. In vivo biodistribution studies apparently showed low affinity to cardiac beta-adrenoceptors. The radiolabelled counterpart 2-(125)I-ICI-H showed a high degree of non-specific binding in vitro and no specific binding to cardiac beta(1)-adrenoceptors in vivo.

CONCLUSION

Because of its high non-specific binding 2-(125)I-ICI-H is no suitable radiotracer for imaging in vivo.

Abstract P5-09-03: Endocrine response in invasive lobular carcinoma is characterized by unique estrogen-mediated gene expression and de novo tamoxifen resistance

Invasive lobular carcinoma (ILC) represents ∼10% of newly diagnosed breast tumors, or ∼30,000 cases annually in the US. However, ILC-specific signaling and endocrine responsiveness are not well characterized. Retrospective analyses suggest that ILC patients treated with endocrine therapy have poorer outcomes than invasive ductal carcinoma (IDC) patients with similar biomarkers, and that ILC patients may not benefit from adjuvant tamoxifen. We hypothesize that estrogen receptor-alpha (ER) regulated gene expression is unique in ILC cells and drives endocrine resistance.

The ER-positive ILC cell lines MDA MB 134VI and SUM44PE were used as in vitro models of cell growth and ER-regulated gene expression in response to estradiol (E2). To examine the ER-regulated transcriptome, we performed gene expression microarray analyses and ER ChIP-Seq following E2 treatment. In parallel, E2 response was assessed in vivo in the primary ILC xenograft HCI-013. Response to endocrine therapies, tamoxifen (Tam), 4-hydroxytamoxifen (4OHT), endoxifen (Bx), and fulvestrant (ICI), were also examined in ILC cell lines.

We observed that E2 induced growth and ER target gene expression in MDA MB 134VI and SUM44PE. We compared our ILC microarray data to published data from ER-positive IDC cell lines (MCF-7, T47D, BT474), and identified 254 genes that were E2-regulated in all 5 cell lines (e.g. GREB1, MYC). 915 genes were E2-regulated only in both ILC cell lines. Consistent with this, roughly half of ER binding sites identified in MDA MB 134VI ChIP-Seq were unique versus published MCF-7 data. We chose a subset of ILC-specific and common E2-regulated genes (n = 107) to assess in vivo using Nanostring gene expression analyses of HCI-013. E2-regulation was observed for 32/107 target genes (30%), suggesting that these genes may be E2-regulated in vivo in ILC patient tumors.

Consistent with clinical data, both ILC cell lines presented de novo tamoxifen resistance. SUM44PE were growth-inhibited by ICI, but unaffected by Tam, 4OHT, or Bx. Similarly, ICI blocked E2-induced growth in MDA MB 134VI, but Tam, 4OHT, and Bx acted as partial agonists, inducing ∼25% growth. Partial agonism was not limited to tamoxifen, as other SERMs (e.g. raloxifene) also induced growth. We then measured ER-regulated gene expression in MDA MB 134VI following tamoxifen treatment. Tam, 4OHT, and Bx acted as agonists for 38/107 genes, whereas ICI acted as an antagonist. All 38 genes were E2-repressed targets (e.g. CCNG2), suggesting that ER-mediated gene repression may be critical to tamoxifen-resistance in ILC. Finally, we observed that FGFR1, frequently amplified in ILC, may be critical for ILC cell survival in the presence of tamoxifen.

These data support the hypothesis that unique ER-mediated gene expression in ILC cells drives endocrine resistance. The de novo tamoxifen resistance observed in ILC cells may correlate with the worse outcomes in ILC patients recently reported. We hypothesize that genes regulated by tamoxifen as an agonist may play a role in tamoxifen-induced growth or serve as biomarkers of resistance. Targeting growth factor signaling using FGFR1 inhibitors may block survival pathways required by ILC cells and reverse tamoxifen resistance.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-09-03.

Giant Lacrimal Gland Cyst in a Pediatric Patient: Case Report and Review of the Literature

Lacrimal gland cysts are rare clinical entities in the pediatric population. Herein is described a 6-year-old male patient presenting with progressive left upper lid ptosis, found to have a large ipsilateral superotemporal orbital mass. Diagnosis of a giant lacrimal gland cyst was confirmed excisional biopsy. Despite the resolution of mechanical blepharoptosis, the patient maintained visual acuity limitation due to suspected deprivation amblyopia. The pathophysiology and clinical manifestations of lacrimal gland cysts in the pediatric population are reviewed to emphasize the importance of expedited identification and management in this patient cohort.