Hypothalamic PVN CRH neurons signal through PVN GABA neurons to suppress GnRH pulse generator frequency in female mice

Corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVN) are central to the stress response. Chemogenetic activation of PVN CRH neurons decreases LH pulse frequency but the mechanism is unknown. In the present study, optogenetic stimulation of PVN CRH neurons suppressed LH pulse frequency in estradiol (E2)-replaced ovariectomised (OVX) CRH-cre mice and this effect was augmented or attenuated by intra-PVN GABAA or GABAB receptor antagonism respectively. PVN CRH neurons signal to local GABA neurons which may provide a possible indirect mechanism by which PVN CRH neurons suppress LH pulse frequency. Optogenetic stimulation of potential PVN GABAergic projection terminals in the hypothalamic arcuate nucleus (ARC) in OVX E2-replaced Vgat-cre-tdTomato mice via an optic fibre implanted in the ARC suppressed LH pulse frequency. To further determine whether PVN CRH neurons signal through PVN GABA neurons to suppress LH pulsatility, we combined recombinase mice with intersectional vectors to selectively target these neurons. CRH-cre::Vgat-FlpO mice expressing the stimulatory opsin, ChRmine in non-GABAergic CRH neurons alone or in combination with the inhibitory opsin NpHR3.3 in non-CRH expressing GABA neurons in the PVN were used. Optogenetic stimulation of non-GABAergic CRH neurons suppressed pulsatile LH secretion, however LH pulse frequency was not affected when CRH neurons were stimulated and PVN GABA neurons were simultaneously inhibited. Together, these studies demonstrate that suppression of LH pulse frequency in response to PVN CRH neuronal activation is mediated by GABAergic signalling intrinsic to the PVN and may incorporate PVN GABAergic projection to the hypothalamic GnRH pulse generator.

Posterodorsal Medial Amygdala Urocortin-3, GABA, and Glutamate Mediate Suppression of LH Pulsatility in Female Mice

The posterodorsal subnucleus of the medial amygdala (MePD) is an upstream modulator of the hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-adrenal (HPA) axes. Inhibition of MePD urocortin-3 (Ucn3) neurons prevents psychological stress-induced suppression of luteinizing hormone (LH) pulsatility while blocking the stress-induced elevations in corticosterone (CORT) secretion in female mice. We explore the neurotransmission and neural circuitry suppressing the gonadotropin-releasing hormone (GnRH) pulse generator by MePD Ucn3 neurons and we further investigate whether MePD Ucn3 efferent projections to the hypothalamic paraventricular nucleus (PVN) control CORT secretion and LH pulsatility. Ucn3-cre-tdTomato female ovariectomized (OVX) mice were unilaterally injected with adeno-associated virus (AAV)-channelrhodopsin 2 (ChR2) and implanted with optofluid cannulae targeting the MePD. We optically activated Ucn3 neurons in the MePD with blue light at 10 Hz and monitored the effect on LH pulses. Next, we combined optogenetic stimulation of MePD Ucn3 neurons with pharmacological antagonism of GABAA or GABAB receptors with bicuculline or CGP-35348, respectively, as well as a combination of NMDA and AMPA receptor antagonists, AP5 and CNQX, respectively, and observed the effect on pulsatile LH secretion. A separate group of Ucn3-cre-tdTomato OVX mice with 17β-estradiol replacement were unilaterally injected with AAV-ChR2 in the MePD and implanted with fiber-optic cannulae targeting the PVN. We optically stimulated the MePD Ucn3 efferent projections in the PVN with blue light at 20 Hz and monitored the effect on CORT secretion and LH pulses. We reveal for the first time that activation of Ucn3 neurons in the MePD inhibits GnRH pulse generator frequency via GABA and glutamate signaling within the MePD, while MePD Ucn3 projections to the PVN modulate the HPG and HPA axes.

GABA Signaling in the Posterodorsal Medial Amygdala Mediates Stress-induced Suppression of LH Pulsatility in Female Mice

Psychological stress is linked to infertility by suppressing the hypothalamic GnRH pulse generator. The posterodorsal subnucleus of the medial amygdala (MePD) is an upstream regulator of GnRH pulse generator activity and displays increased neuronal activation during psychological stress. The MePD is primarily a GABAergic nucleus with a strong GABAergic projection to hypothalamic reproductive centers; however, their functional significance has not been determined. We hypothesize that MePD GABAergic signalling mediates psychological stress-induced suppression of pulsatile LH secretion. We selectively inhibited MePD GABA neurons during psychological stress in ovariectomized (OVX) Vgat-cre-tdTomato mice to determine the effect on stress-induced suppression of pulsatile LH secretion. MePD GABA neurons were virally infected with inhibitory hM4DGi-designer receptor exclusively activated by designer drugs (DREADDs) to selectively inhibit MePD GABA neurons. Furthermore, we optogenetically stimulated potential MePD GABAergic projection terminals in the hypothalamic arcuate nucleus (ARC) and determined the effect on pulsatile LH secretion. MePD GABA neurons in OVX female Vgat-cre-tdTomato mice were virally infected to express channelrhodopsin-2 and MePD GABAergic terminals in the ARC were selectively stimulated by blue light via an optic fiber implanted in the ARC. DREADD-mediated inhibition of MePD GABA neurons blocked predator odor and restraint stress-induced suppression of LH pulse frequency. Furthermore, sustained optogenetic stimulation at 10 and 20 Hz of MePD GABAergic terminals in the ARC suppressed pulsatile LH secretion. These results show for the first time that GABAergic signalling in the MePD mediates psychological stress-induced suppression of pulsatile LH secretion and suggest a functionally significant MePD GABAergic projection to the hypothalamic GnRH pulse generator.

RF01 | PMON45 Urocortin 3 Interaction with GABA and Glutamate in the Posterodorsal Subnucleus of The Medial Amygdala Mediates Suppression of GnRH Pulse Generator Frequency in Female Mice

Stress exerts a profound impact on reproductive function and disrupts pulsatile luteinizing hormone (LH) secretion. The posterodorsal subnucleus of the medial amygdala (MePD) is an upstream modulator of the hypothalamus pituitary gonadal axis. Stress alters neuronal activity within the MePD, increasing the expression of Urocortin3 (Ucn3) while enhancing the inhibitory output from the MePD to key hypothalamic reproductive centres. Designer receptor exclusively activated by designer drugs (DREADDs) inhibition of MePD Ucn3 neurons prevents psychological stress-induced suppression of LH pulses in female mice. The neurochemical pathways in the MePD responsible for regulating the GnRH pulse generator in the presence of stress remain unknown. We investigate the neurotransmission involved in the neural circuitry responsible for the suppression of GnRH pulse generator activity by MePD Ucn3 neuronal activation. Ucn3-Cre-tdTomato female ovariectomised (OVX) mice were unilaterally injected with AAV-ChR2 and implanted with optofluid cannulae targeting the MePD. Firstly, we optically stimulated MePD Ucn3 neurons with blue light at 10 Hz, 10 mW and monitored the effect on LH pulses. Next, we combined optogenetic activation of MePD Ucn3 neurons with pharmacological antagonism of GABAA or GABAB receptors with bicuculline or CGP, respectively, and observed the effect on LH pulsatility. Finally, during optical activation of MePD Ucn3 neurons we administered a combination of NMDA and AMPA receptor antagonists, AP5 and CNQX respectively, and monitored the effect on pulsatile LH secretion. Optogenetic stimulation of MePD Ucn3 neurons suppressed pulsatile LH secretion compared to controls and administration of aCSF had no effect on LH pulse interval (MePD Ucn3 activation: 36.04 ± 2.49 vs. pre-treatment control period: 17.50 ± 0.67 vs control virus: 21.67 ± 1.67 min; mean ± SEM; p<0.0001; n=12). Intra-MePD infusion of bicuculline (BIC) or CGP during optogenetic stimulation of MePD Ucn3 neurons completely blocked the suppressive effect of MePD Ucn3 neuronal activation on LH pulsatility (MePD Ucn3 activation and BIC: 20.50 ± 2.03 vs. pre-treatment control period: 17.58 ± 0.75 min; MePD Ucn3 activation and CGP: 16.30 ± 0.63 vs. pre-treatment control period: 17.50 ± 0.77 min; n=7-10). Intra-MePD infusion of AP5 + CNQX during optogenetic stimulation of MePD Ucn3 neurons similarly completely blocked the suppressive effect of MePD Ucn3 neuronal activation on LH pulsatility (MePD Ucn3 activation and AP5 + CNQX: 19.58 ± 1.42 min; n=6). Our findings show for the first time that optogenetic stimulation of MePD Ucn3 neurons inhibits GnRH pulse generator activity via GABA and glutamate signalling within the MePD.

Presentation: Saturday, June 11, 2022 1:12 p.m. - 1:17 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

GnRH pulse generator frequency is modulated by kisspeptin and GABA-glutamate interactions in the posterodorsal medial amygdala in female mice

Kisspeptin neurons in the arcuate nucleus of the hypothalamus generate gonadotrophin-releasing hormone (GnRH) pulses, and act as critical initiators of functional gonadotrophin secretion and reproductive competency. However, kisspeptin in other brain regions, most notably the posterodorsal subnucleus of the medial amygdala (MePD), plays a significant modulatory role over the hypothalamic kisspeptin population; our recent studies using optogenetics have shown that low-frequency light stimulation of MePD kisspeptin results in increased luteinsing hormone pulse frequency. Nonetheless, the neurochemical pathways that underpin this regulatory function remain unknown. To study this, we have utilised an optofluid technology, precisely combining optogenetic stimulation with intra-nuclear pharmacological receptor antagonism, to investigate the neurotransmission involved in this circuitry. We have shown experimentally and verified using a mathematical model that functional neurotransmission of both GABA and glutamate is a requirement for effective modulation of the GnRH pulse generator by amygdala kisspeptin neurons.

OR17-2 GABAergic Signalling in the Posterodorsal Medial Amygdala Mediates Psychological Stress-induced Suppression of the GnRH Pulse Generator in Female Mice

Psychological stress is linked to infertility and reproductive dysfunction by suppressing the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator and pulsatile luteinising hormone (LH) secretion. The posterodorsal subnucleus of the medial amygdala (MePD) is a key upstream regulator of GnRH pulse generator activity and displays increased neuronal activation in response to psychological stressors. The MePD is primarily a GABAergic nucleus with a strong GABAergic projection to hypothalamic reproductive centres, however, their functional significance has not been determined. We hypothesis that MePD GABAergic signalling is a crucial mediator of psychological stress-induced suppression of pulsatile LH secretion. We used a chemogenetic approach to selectively silence MePD GABA neurones during psychological stress to determine the effect on pulsatile LH secretion. Female ovariectomised Vgat-cre mice (n=7) were virally infected to selectively express inhibitory hM4DGi-DREADDs in MePD GABA neurones. Mice were exposed to either predator odour (PO) or restraint stress and given an intraperitoneal injection of either saline or the DREADD chemical activator clozapine-N-oxide (CNO, 5mg/kg). Statistical significance was determined using a one-way ANOVA and post-hoc Tukey test. Data are presented as mean ± SEM and p<0.05 was considered significant. PO exposure significantly increased LH inter-pulse interval (IPI) in the saline group (prestress: 19.05 ± 1.16 min vs. PO: 29.28 ± 3.16 min, p<0.05, n=7) and this effect was blocked by DREADD-mediated inhibition of MePD GABA neurones (prestress: 20.59 ± 1.12 min vs. PO: 21.31 ± 1.76 min, p>0.05, n=7). Restraint stress dramatically increased LH IPI in the saline group (prestress: 17.78 ± 1.02 min vs. restraint: 45.71 ± vs 5.50 min, p<0.05, n=7) and DREADD-mediated inhibition of MePD GABA neurones blocked this effect (prestress: 18.57 ± 1.97 min vs. restraint: 27.26 ± 4.02 min, p>0.05, n=7). Direct projections from the MePD to the GnRH pulse generator in the hypothalamic arcuate nucleus (ARC) have been identified, however, their phenotype is unknown. In this study, we optogenetically stimulated potential MePD GABAergic projection neurone terminals in the ARC and determined the effect on LH IPI. MePD GABA neurones in female Vgat-cre ovariectomised mice (n=6) were virally infected to express channelrhodopsin 2 protein and MePD GABAergic terminals in the ARC were selectively stimulated by blue light via a chronically implanted fibre-optic cannula in the ARC. Sustained optogenetic stimulation at 10 and 20Hz of MePD GABAergic terminals in the ARC dose-dependently suppressed pulsatile LH secretion (LH IPI; control: 23.34 ± 2.11 min vs. 10Hz: 38.08 ± 3.61 min; 20Hz: 56.67 ± 3.33 min, p<0.05, n=6). These findings confirm a functionally significant MePD GABAergic projection to the ARC and highlight the importance of GABA signalling in the MePD in mediating stress-induced suppression of reproductive function. Collectively, these findings provide novel insight into the amygdala neural circuitry underpinning stress-induced reproductive function.

Presentation: Sunday, June 12, 2022 11:15 a.m. - 11:30 a.m.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Role of Posterodorsal Medial Amygdala Urocortin-3 in Pubertal Timing in Female Mice

Post-traumatic stress disorder impedes pubertal development and disrupts pulsatile LH secretion in humans and rodents. The posterodorsal sub-nucleus of the medial amygdala (MePD) is an upstream modulator of the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator, pubertal timing, as well as emotional processing and anxiety. Psychosocial stress exposure alters neuronal activity within the MePD increasing the expression of Urocortin3 (Ucn3) and its receptor corticotropin-releasing factor type-2 receptor (CRFR2) while enhancing the inhibitory output from the MePD to key hypothalamic reproductive centres. We test the hypothesis that psychosocial stress, processed by the MePD, is relayed to the hypothalamic GnRH pulse generator to delay puberty in female mice. We exposed C57Bl6/J female mice to the predator odor, 2,4,5-Trimethylthiazole (TMT), during pubertal transition and examined the effect on pubertal timing, pre-pubertal LH pulses and anxiety-like behaviour. Subsequently, we virally infected Ucn3-cre-tdTomato female mice with stimulatory DREADDs targeting MePD Ucn3 neurons and determined the effect on pubertal timing and pre-pubertal LH pulse frequency. Exposure to TMT during pubertal development delayed puberty, suppressed pre-pubertal LH pulsatility and enhanced anxiety-like behaviour, while activation of MePD Ucn3 neurons reduced LH pulse frequency and delayed puberty. Early psychosocial stress exposure decreases GnRH pulse generator frequency delaying puberty while inducing anxiety-behaviour in female mice, an effect potentially involving Ucn3 neurons in the MePD.

Urocortin3 in the Posterodorsal Medial Amygdala Mediates Stress-induced Suppression of LH Pulsatility in Female Mice

Psychosocial stress disrupts reproduction and interferes with pulsatile LH secretion. The posterodorsal medial amygdala (MePD) is an upstream modulator of the reproductive axis and stress. Corticotropin-releasing factor type 2 receptors (CRFR2s) are activated in the presence of psychosocial stress together with increased expression of the CRFR2 ligand Urocortin3 (Ucn3) in the MePD of rodents. We investigate whether Ucn3 signalling in the MePD is involved in mediating the suppressive effect of psychosocial stress on LH pulsatility. First, we administered Ucn3 into the MePD and monitored the effect on LH pulses in ovariectomized mice. Next, we delivered Astressin2B, a selective CRFR2 antagonist, intra-MePD in the presence of predator odor, 2,4,5-trimethylthiazole (TMT) and examined the effect on LH pulses. Subsequently, we virally infected Ucn3-cre-tdTomato mice with inhibitory designer receptor exclusively activated by designer drugs (DREADDs) targeting MePD Ucn3 neurons while exposing mice to TMT or restraint stress and examined the effect on LH pulsatility as well as corticosterone release. Administration of Ucn3 into the MePD dose-dependently inhibited LH pulses and administration of Astressin2B blocked the suppressive effect of TMT on LH pulsatility. Additionally, DREADDs inhibition of MePD Ucn3 neurons blocked TMT and restraint stress-induced inhibition of LH pulses and corticosterone release. These results demonstrate for the first time that Ucn3 neurons in the MePD mediate psychosocial stress-induced suppression of the GnRH pulse generator and corticosterone secretion. Ucn3 signalling in the MePD plays a role in modulating the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axes, and this brain locus may represent a nodal center in the interaction between the reproductive and stress axes.

Modulation of pulsatile GnRH dynamics across the ovarian cycle via changes in the network excitability and basal activity of the arcuate kisspeptin network

Pulsatile GnRH release is essential for normal reproductive function. Kisspeptin secreting neurons found in the arcuate nucleus, known as KNDy neurons for co-expressing neurokinin B, and dynorphin, drive pulsatile GnRH release. Furthermore, gonadal steroids regulate GnRH pulsatile dynamics across the ovarian cycle by altering KNDy neurons' signalling properties. However, the precise mechanism of regulation remains mostly unknown. To better understand these mechanisms, we start by perturbing the KNDy system at different stages of the estrous cycle using optogenetics. We find that optogenetic stimulation of KNDy neurons stimulates pulsatile GnRH/LH secretion in estrous mice but inhibits it in diestrous mice. These in vivo results in combination with mathematical modelling suggest that the transition between estrus and diestrus is underpinned by well-orchestrated changes in neuropeptide signalling and in the excitability of the KNDy population controlled via glutamate signalling. Guided by model predictions, we show that blocking glutamate signalling in diestrous animals inhibits LH pulses, and that optic stimulation of the KNDy population mitigates this inhibition. In estrous mice, disruption of glutamate signalling inhibits pulses generated via sustained low-frequency optic stimulation of the KNDy population, supporting the idea that the level of network excitability is critical for pulse generation. Our results reconcile previous puzzling findings regarding the estradiol-dependent effect that several neuromodulators have on the GnRH pulse generator dynamics. Therefore, we anticipate our model to be a cornerstone for a more quantitative understanding of the pathways via which gonadal steroids regulate GnRH pulse generator dynamics. Finally, our results could inform useful repurposing of drugs targeting the glutamate system in reproductive therapy.

An analysis of Canadian doctor of pharmacy hospital preceptor experiences in alternative preceptor models

OBJECTIVE

To describe pharmacy preceptors' experiences in alternative preceptor models and their perceptions of these models' impact on the knowledge, skills, attitudes, behaviors, and professional practices of both themselves and their students.

METHODS

Pharmacy preceptors with experience using alternative preceptor models participated in semi-structured interviews. Models included peer-assisted learning (PAL) (≥ two students of the same educational level), near-peer teaching (NPT) (≥ one junior student with ≥ one senior student), and co-preceptorship (CoP) (≥ two preceptors). Interviews were transcribed, coded, and analyzed for themes using the Kirkpatrick framework for evaluating educational interventions.

RESULTS

Twenty hospital pharmacy preceptors from 13 institutions were interviewed, and 13 themes were identified. Fourteen preceptors had experience with PAL, 9 with NPT, and 9 with CoP. Preceptors perceived that NPT and PAL fostered comfortable learning environments that supported student success; challenges included increased time teaching multiple students and completing evaluations. CoP allowed preceptors to balance teaching with clinical duties while broadening students' exposure to different practice settings. Preceptors improved skills in time management, communicating feedback, and adapting to individual students' learning needs and styles. Alternative models enabled preceptors to provide care to more patients and complete projects, thus extending their professional practice. They also described that students participating in these models developed a sense of responsibility for patient care and will be primed to work collaboratively with pharmacy colleagues in the future.

CONCLUSIONS

Preceptors expressed satisfaction with alternative preceptor models. The models enhanced the learning, skill development, and professional practice of both preceptors and students.

Does instillation of lidocaine gel following flexible cystoscopy decrease the severity of post procedure symptoms? A randomised controlled trial assessing the efficacy of lidocaine gel post flexible cystoscopy

Objective

To assess whether instillation of lidocaine gel both before and after flexible cystoscopy is more effective at reducing post procedural symptoms than instillation of lidocaine gel pre flexible cystoscopy alone. We hypothesise that inadequate urethral dwell time and dilution of lidocaine gel by the irrigation fluid during flexible cystoscopy limits its anaesthetic efficacy. Only one other study has attempted to reduce bothersome urinary symptoms through an intervention after flexible cystoscopy.

Methods

This was a randomised controlled trial in which patients were randomised 1:1 to receive lidocaine gel pre and post flexible cystoscopy (treatment) or lidocaine gel pre flexible cystoscopy only (control). Patient-reported outcome measures were used to assess symptoms and quality of life prior to cystoscopy, on day 2 and day 7 post cystoscopy.

Result

Fifty patients were divided equally between the treatment and control groups. There were no significant differences in baseline characteristics between the groups (p = 1.000). An overall symptoms variable was measured, though no significant difference was found in the distribution of responses between the groups at baseline, 2 or 7 days after the flexible cystoscopy (p = 0.423, 0.651,0.735). In the treatment group, 1 patient (4.0%) presented to a doctor for review following flexible cystoscopy, and 4 patients (16.0%) presented in the control group (p = 0.349).

Conclusion

Initial study results suggest that post-operative lidocaine does not significantly limit the exacerbation of urinary symptoms following flexible cystoscopy; however, our results are not powered to detect a small difference. We do not recommend a change in practice based on our results.

Obstructive Sleep Apnea in Obese Patients: a UK Population Analysis

Background

Obstructive sleep apnea (OSA) is an increasingly common disorder associated with increased cardiovascular disease, mortality, reduced productivity, and an increased risk of road traffic accidents. A significant proportion of patients with OSA in the UK are undiagnosed. This study aims to identify risk factors for OSA in an obese cohort.

Method

A population-based study was conducted of obese patients (BMI ≥ 30 kg/m²) from the Clinical Practice Research Datalink (CPRD). A logistic regression model was used to calculate odds ratios (ORs) for developing OSA according to other clinicopathological characteristics. Multivariate analysis was conducted of individual factors that affect the propensity to develop OSA. Statistical significance was defined as p < 0.050.

Results

From 276,600 obese patients identified during a data extraction of the CPRD in July 2017, the prevalence of OSA was 5.4%. The following risk factors were found to be independently associated with increased likelihood of OSA: male sex (OR = 3.273; p < 0.001), BMI class II (OR = 1.640; p < 0.001), BMI class III (OR = 3.768; p < 0.001), smoking (OR = 1.179; p < 0.001), COPD (OR = 1.722; p < 0.001), GERD (OR = 1.557; p < 0.001), hypothyroidism (OR = 1.311; p < 0.001), acromegaly (OR = 3.543; p < 0.001), and benzodiazepine use (OR = 1.492; p < 0.001). Bariatric surgery was associated with reduced risk of OSA amongst this obese population (OR = 0.260; p < 0.001).

Conclusions

In obese patients, there are numerous comorbidities that are associated with increased likelihood of OSA. These factors can help prompt clinicians to identify undiagnosed OSA. Bariatric surgery appears to be protective against developing OSA.

Development and Validation of Nine Deprescribing Algorithms for Patients on Hemodialysis to Decrease Polypharmacy

Background:

Polypharmacy is ubiquitous in patients on hemodialysis (HD), and increases risk of adverse events, medication interactions, nonadherence, and mortality. Appropriately applied deprescribing can potentially minimize polypharmacy risks. Existing guidelines are unsuitable for nephrology clinicians as they lack specific instructions on how to deprescribe and which safety parameters to monitor.

Objective:

To develop and validate deprescribing algorithms for nine medication classes to decrease polypharmacy in patients on HD.

Design:

Questionnaires and materials sent electronically.

Participants:

Nephrology practitioners across Canada (nephrologists, nurse practitioners, renal pharmacists).

Methods:

A literature search was performed to develop the initial algorithms via Lynn’s method for development of content-valid clinical tools. Content and face validity of the algorithms was evaluated over three interview rounds using Lynn’s method for determining content validity. Canadian nephrology clinicians each evaluated three algorithms (15 clinicians per round, 45 clinicians in total) by rating each algorithm component on a four-point Likert scale for relevance; face validity was rated on a five-point scale. After each round, content validity index of each component was calculated and revisions made based on feedback. If content validity was not achieved after three rounds, additional rounds were completed until content validity was achieved.

Results:

After three rounds of validation, six algorithms achieved content validity. After an additional round, the remaining three algorithms achieved content validity. The proportion of clinicians rating each face validity statement as “Agree” or “Strongly Agree” ranged from 84% to 95% (average of all five questions, across three rounds).

Limitations:

Algorithm development was guided by existing deprescribing protocols intended for the general population and the expert opinions of our study team, due to a lack of background literature on HD-specific deprescribing protocols. There is no universally accepted method for the validation of clinical decision-making tools.

Conclusions:

Nine medication-specific deprescribing algorithms for patients on HD were developed and validated by clinician review. Our algorithms are the first medication-specific, patient-centric deprescribing guidelines developed and validated for patients on HD.

SUN-LB49 Chronic Exposure to Predator Odour Stress Disrupts LH Pulsatility and Delays Puberty While Activation of Amygdala Kisspeptin Advances Puberty

Chronic exposure to predator odour stress disrupts LH pulsatility and delays puberty whileactivation of amygdala kisspeptin advances pubertyDeyana Ivanova MS¹, Xiao Feng Li MD/PhD¹, Caitlin Mcintyre BS¹, and Kevin O’Byrne PhD¹; ¹Department of Women and Children’s Health, Faculty of Life Science and Medicine, King’sCollege London, UKPost-traumatic stress (PTSD) is associated with altered pubertal timing and predator odourexposure is a classical rodent PTSD model. Kisspeptin neurones in the posterodorsal sub-nucleus of the medial amygdala (MePD) are thought to modulate pubertal timing and anxiety.We test the hypothesis that psychosocial stress, processed by the MePD, is relayed to theGnRH pulse generator to delay puberty. Female mice were exposed to predator odour, 2,4,5-Trimethylthiazole (TMT), for 14 days from postnatal day (pnd) 21 and pubertal onset wasmonitored. Anxiety was tested using the Elevated Plus Maze (EPM), Light/Dark Box (LDB) andsocial interaction (SI). The effect of TMT on luteinizing hormone (LH) pulses was measured,on pnd 26 and 29. Additionally, kisspeptin-cre mice were bilaterally injected with hM3Dq-DREADD AAV in the MePD at pnd 13. From pnd 21, CNO was administered via drinking waterfor 14 days and pubertal onset was monitored. The TMT-mice showed a significant delay offirst estrous (FE; TMT: 38.1 ± 0.5 vs. control: 33.3 ± 0.6 days; p<0.0001; n=10-14) withoutaffecting body weight (BW; p=0.9; n=10-14). TMT-mice spent less time exploring the openarm of the EPM (TMT: 13 ± 3 vs. control: 32 ± 5 secs; p<0.05; n=10-14) and in the lightcompartment of the LDB (TMT: 117 ± 12 vs. control: 162 ± 15 secs; p<0.05; n=10-14), whileengaging less in SI (TMT: 26.8 ± 2.8 vs. control: 47.7 ± 8.8 secs; p<0.05; n=10-14) during TMT-exposure compared to controls. The TMT group exhibited a reduction in LH pulse frequencyon pnd 26 (TMT: 0.2 ± 0.2 vs. control: 1.7 ± 0.4 pulses/2 h; p<0.05; n=6-9) and 29 (TMT: 0.6 ±0.2 vs. control: 2.6 ± 0.4 pulses/2 h; p<0.001; n=6-9). DREADD activation of kisspeptinneurones in the MePD advances FE (DREADD: 30 ± 1 vs. control 34.67 ± 0.82 days; p<0.05;n=6) without affecting BW (p=0.9; n=6). Predator odour stress reduces GnRH pulse generatorfrequency, delays puberty and enhances anxiety-like behaviour, while selective chemogeneticactivation of kisspeptin neurones in the MePD advances puberty in female mice.

An Analysis of Canadian Doctor of Pharmacy Student Experiences in Non-Traditional Student-Preceptor Models

Objective. To describe students' experiences and perceptions of non-traditional student-preceptor learning models and evaluate the effectiveness of these models on students' learning experience. Methods. Pharmacy students who had completed at least one experiential rotation with a non-traditional learning model participated in semi-structured interviews. Models included peer-assisted learning (PAL; two or more students of same educational level), near-peer teaching (NPT; one or more junior students with one or more senior students), and co-preceptorship (CoP; two or more preceptors). Interviews were transcribed, coded, and analyzed for themes. Themes were mapped according to the Kirkpatrick model for evaluating educational training. Results. Twenty semi-structured interviews were conducted. Forty-three experiences (19 CoP, 14 PAL, 10 NPT) from 14 institutions were described. Many themes overlapped between the three models. In CoP, learners described increased preceptor availability and exposure to different patient care approaches. Challenges arose when preceptors had different expectations. Students overwhelmingly endorsed a multi-learner environment. Both PAL and NPT learners felt supported as collaboration with other learners was readily fostered. Potential challenges in PAL and NPT were difficulties when personalities conflicted and when there was a significant knowledge gap between the learners. All three models allowed for the development of skills, including communication and collaboration. Learners reported an enhanced approach to patient care and professional practice, including approaches to teaching as new preceptors. Conclusion. Pharmacy students and graduates valued their experiences in non-traditional student-preceptor models. Institutions may find support for using these precepting models to increase placement capacity.

Does fluoroscopy prevent inadvertent parathyroidectomy in thyroid surgery?

INTRODUCTION

Near-infrared imaging may facilitate intraoperative identification of parathyroid glands by causing autofluorescence but its clinical value has not been established. Inadvertent parathyroidectomy occurs in 5-22% of thyroidectomies and is associated with temporary and permanent hypoparathyroidism. The aim of this study was to determine whether near-infrared imaging prevents inadvertent parathyroidectomy and early hypocalcaemia as a surrogate for permanent hypoparathyroidism.

MATERIALS AND METHODS

Near-infrared imaging was used in a prospective cohort of consecutive thyroidectomies. Thyroidectomies performed prior to the introduction of near-infrared imaging formed a control group. The thyroid bed and specimen were scanned with near-infrared imaging. Areas of autofluorescence on the specimen were examined and any parathyroid tissue found was autotransplanted. Inadvertent parathyroidectomy was therefore recorded as established intraoperatively by near-infrared imaging (allowing autotransplantation) or on subsequent histology (missed). Serum calcium and parathyroid hormone were measured on day one and at two weeks and six months postoperatively.

RESULTS

A total of 269 patients were included: 106 near-infrared imaging and 163 controls. Inadvertent parathyroidectomy was detected by near-infrared imaging in two (and autotransplantation performed) and histologically (i.e. missed by near-infrared imaging in 13, 12.3% vs 17, 10.4% controls). Neither result was statistically significant (P = 0.08, 0.89). There was no significant difference in serum calcium or parathyroid hormone between near-infrared imaging and control groups at one day, two weeks or thereafter.

DISCUSSION

Near-infrared imaging may detect inadvertent parathyroidectomy and may allow autotransplantation. It did not, however, reduce the incidence of missed inadvertent parathyroidectomy and no difference was seen in early hypocalcaemia or late hypoparathyroidism. Current near-infrared imaging technology does not appear to confer a clinical benefit sufficient to justify its use.

A critical review of thyroidectomy consent in the UK

BACKGROUND

In 2015-16, the National Health Service (NHS) Litigation Authority received 10,965 claims for clinical negligence, with surgery having the highest number of claims. Currently a sum amounting to 25% of the annual NHS budget has been ring-fenced to meet extant claims. Claims made on a basis of inadequate informed consent are increasingly seen with many achieving a successful plaintiff outcome. There are presently no UK guidelines for thyroidectomy consent.

METHOD

A prospective study was performed to investigate current consent practice among the British Association of Endocrine and Thyroid Surgeons (BAETS) membership and patients having previously undergone thyroidectomy. For surgeons, the Bolam legal test applied where surgeons declared what risks and complications they routinely consented for during their practice. A study was also undertaken in patients who had previously undergone thyroidectomy for cancer applying the rule of Montgomery.

RESULTS

Consent practice from 193 surgeons and data from 415 patients was analysed. In total thyroidectomy for cancer, 95% of surgeons consent for Recurrent Laryngeal Nerve (RLN) injury and temporary or permanent voice change. 70% specifically consent for External Laryngeal Nerve (ELN) injury, 50% for tracheostomy and 55% for general anaesthetic associated complications. Analysis of patient data showed they would like to be consented for far more risks than they are presently informed about in general medical practice. There was significant variation in the consenting practice in BAETS surgeons.

CONCLUSION

A BAETS approved consensus guideline to standardise UK consent practice would be appropriate. This may reduce complaints, litigation claims and guide expert witnesses.

Temperature and moisture are minor drivers of regional-scale soil organic carbon dynamics

Storing large amounts of organic carbon, soils are a key but uncertain component of the global carbon cycle, and accordingly, of Earth System Models (ESMs). Soil organic carbon (SOC) dynamics are regulated by a complex interplay of drivers. Climate, generally represented by temperature and moisture, is regarded as one of the fundamental controls. Here, we use 54 forest sites in Switzerland, systematically selected to span near-independent gradients in temperature and moisture, to disentangle the effects of climate, soil properties, and landform on SOC dynamics. We estimated two SOC turnover times, based on bulk soil ¹⁴C measurements (τ_14C) and on a 6-month laboratory soil incubation (τ_i). In addition, upon incubation, we measured the ¹⁴C signature of the CO₂ evolved and quantified the cumulated production of dissolved organic carbon (DOC). Our results demonstrate that τ_i and τ_14C capture the dynamics of contrasting fractions of the SOC continuum. The ¹⁴C-based τ_14C primarily reflects the dynamics of an older, stabilised pool, whereas the incubation-based τ_i mainly captures fresh readily available SOC. Mean site temperature did not raise as a critical driver of SOC dynamics, and site moisture was only significant for τ_i. However, soil pH emerged as a key control of both turnover times. The production of DOC was independent of τ_i and not driven by climate, but primarily by the content of clay and, secondarily by the slope of the site. At the regional scale, soil physicochemical properties and landform appear to override the effect of climate on SOC dynamics.

Observation of Mode-Locked Spatial Laser Solitons

A stable nonlinear wave packet, self-localized in all three dimensions, is an intriguing and much sought after object in nonlinear science in general and in nonlinear photonics in particular. We report on the experimental observation of mode-locked spatial laser solitons in a vertical-cavity surface-emitting laser with frequency-selective feedback from an external cavity. These spontaneously emerging and long-term stable spatiotemporal structures have a pulse length shorter than the cavity round-trip time and may pave the way to completely independent cavity light bullets.

Strong Quantum Coherence between Fermi Liquid Mahan Excitons

In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.

Cost disparity between health care systems--it's not the surgeons: A cost analysis of thyroid cancer care between the United States and France

BACKGROUND

The cost disparity between the United States and other advanced health care systems, including France, is expanding. In this report we identified the management of papillary thyroid cancer (PTC) that contribute to reimbursement disparity.

METHODS

A tri-institutional, retrospective review included 200 patients with PTC (100 from the United States, 100 from France) treated by total thyroidectomy with/without central neck dissection. A cost model was generated incorporating perioperative management variables (within 1 year) and their reimbursement rates according to the 2014 US Medicare and French government fee-schedules.

RESULTS

In the United States, total thyroidectomy with central neck dissection was more frequent (92% vs 35%, P < .001), median duration of stay was less (1 vs 3 days, P < .001), and use of radioactive iodine was less (66% vs 93%, P < .001), although Thyrogen stimulation was more prevalent (100% vs 43%, P < .001). Overall, the median cost per patient was greater in the United States ($14,069 vs $4,590, P < .001). Reimbursements to the hospital facility accounted for 70% of the disparity, despite lesser durations of stay. Nuclear medicine accounted for 19%, mostly from Thyrogen reimbursement despite less use of radioactive iodine. Surgeon fees accounted for 6%, followed by office visits, laboratory/imaging, anesthesia/pathology fees, and medications.

CONCLUSION

The costs of management of PTC are substantially greater in the US compared with France. Efforts to decrease this disparity should focus on reimbursements for hospital facility and use of nuclear medicine imaging.

Use of a population pharmacokinetic approach for the clinical development of a fixed-dose subcutaneous formulation of trastuzumab

A new subcutaneous (s.c.) trastuzumab formulation provides savings in terms of time and is preferred by patients and health care professionals relative to standard intravenous (i.v.) administration due to simpler and more rapid administration (2-5 minutes). Selection of the s.c. dose was based on a pharmacokinetic bridging approach that aimed to achieve noninferior trastuzumab serum trough concentrations (Ctrough) vs. reference i.v. administration. Using population modeling and simulation, we showed that a fixed 600-mg trastuzumab s.c. dose, administered thrice-weekly (Q3W) without a loading dose, would provide Ctrough (predose Cycle 8) and area under the time-concentration curve (AUC0-21 days, Cycle 7) at least as high as Q3W i.v. administration. The model was retrospectively validated using observed pharmacokinetic data from an independent phase III study of (neo)adjuvant trastuzumab (HannaH). These results provide a strong pharmacokinetic rationale for the trastuzumab s.c. 600-mg fixed dose, supported by the noninferior efficacy of this regimen vs. reference i.v. administration.CPT Pharmacometrics Syst. Pharmacol. (2014) 3, e87; doi:10.1038/psp.2013.63; advance online publication 2 January 2014.

Transplantation at the nexus of behavioral economics and health care delivery

The transplant surgeon's decision to accept and utilize an organ typically is made within a constrained time window, explicitly cognizant of numerous health-related risks and under the potential influence of considerable regulatory and institutional pressures. This decision affects the health of two distinct populations, those patients receiving organ transplants and those waiting to receive a transplant; it also influences the physician's life and their institute's productivity. The numerous, at times nonaligned, incentives established by the complex clinical and regulatory environment, have been derived specifically to influence physicians' behaviors, and though well intended, may lead to responses that are nonoptimal when considering the myriad stakeholders being influenced. This may compromise the quality of care provided to the population at risk, and has potential to influence the physician-patient relationship. A synergistic collaboration between transplant physicians and economists that is focused on this decision environment may help to alleviate these strains. This viewpoint discusses behavioral economic principles and how they might be applied to transplantation. Specifically, the previous medical decision-making literature on transplantation will be reviewed and a discussion on how a behavioral model of physician decision making can be utilized will be explored. To date this approach has not been integrated into transplantation decision making.

Development of a subcutaneous formulation for trastuzumab - nonclinical and clinical bridging approach to the approved intravenous dosing regimen

A subcutaneous (SC) formulation has been developed for the humanized monoclonal antibody (mAb) trastuzumab as an alternative to established intravenous (IV) infusion. The ready-to-use liquid SC formulation is injected as a fixed dose in approximately 5 min, which is expected to increase patient's convenience, reduce pharmacy preparation time, and administration costs overall.The trastuzumab dose as well as the dose of recombinant human hyaluronidase (rHuPH20), an enzyme that enables SC administration of volumes larger than 2 mL, was selected based on nonclinical xenograft, pharmacology, and pharmacokinetics mouse and minipig studies.The basic assumption for bridging from the IV to the SC regimen was that comparable trastuzumab serum trough concentrations would result in comparable efficacy. This hypothesis is confirmed by the results from the Phase 3 study in the neo-adjuvant/adjuvant setting. The safety profiles of the trastuzumab SC and IV formulations are comparable and consistent with the known safety profile of trastuzumab.

Adler synchronization of spatial laser solitons pinned by defects

Defects due to growth fluctuations in broad-area semiconductor lasers induce pinning and frequency shifts of spatial laser solitons. The effects of defects on the interaction of two solitons are considered in lasers with frequency-selective feedback both theoretically and experimentally. We demonstrate frequency and phase synchronization of paired laser solitons as their detuning is varied. In both theory and experiment the locking behavior is well described by the Adler model for the synchronization of coupled oscillators.

Phase I clinical study to select a novel oral formulation for ibandronate containing the excipient sodium N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC)

The aim of this study was to select a novel oral formulation for ibandronate (IBN, CAS number: 13892619). In four cohorts of 28, 21, 19 and 29 healthy volunteers, the impact of the carrier molecule sodium N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC, CAS number: 203787-91-1) on the bioavailability of IBN was investigated. Within each cohort different oral formulations with one dose of ibandronate (30 mg) and three different ratios of IBN:SNAC (1:5, 1:10 and 1:20) were compared to the approved oral IBN tablet formulations (150 and 50 mg IBN) in a 4-way cross-over design and a one week washout between the administrations. The highest mean IBN exposure was achieved with a capsule formulation containing drug-coated beadlets and an IBN:SNAC ratio of 1:5. AUC(last) and C(max) of IBN were approximately 1.3- and 2.2-fold higher compared to the reference treatment (150 mg IBN without SNAC). Increasing the post-dose fasting duration from 15 to 30 min resulted in a more than 2-fold increase in AUC(last), while superimposable IBN serum concentration-time profiles were achieved after a 30 and 60 min fast. The tolerability of the IBN/SNAC treatments in all cohorts was similar to that in the IBN reference groups and most adverse events (AEs) were of mild to moderate intensity.

Uptake and behavioural and attitudinal determinants of immunization in an expanded routine infant hepatitis B vaccination program in British Columbia

INTRODUCTION

British Columbia (BC) implemented a universal infant hepatitis B (HB) immunization program in 2001. The study objective was to evaluate HB immunization coverage among the first six-month cohort of eligible infants in the province outside of the Vancouver-Richmond health region and to assess parent/guardian behavioural and attitudinal determinants of HB immunization.

METHODS

A cross-sectional survey of HB immunization was conducted using a random sample of eligible infants born between 1 January-30 June 2001. HB immunization coverage data were obtained from the provincial Public Health Information System, and through a telephone survey of 487 of eligible infants' parents/guardians that was conducted between October 2002-January 2003. At this time, parents/guardians were also asked about behaviours and attitudes towards immunization, based on the Immunization Health Belief Model Scale.

RESULTS

HB immunization coverage with at least one dose of HB vaccine was 89% and uptake of 3 doses of HB vaccine was 78%. HB immunization was significantly associated (p<0.001) with a recommendation for HB immunization from a health care professional. The main reason for non-HB immunization was parental concern about side effects.

DISCUSSION

Seventy-eight percent of infants completed the 3-dose HB vaccination schedule. Parental behaviour regarding HB immunization of their children was strongly influenced by a supportive recommendation from either a nurse or doctor.

Gas jet as a waveguide for air-coupled ultrasound

The directional characteristics of an ultrasonic signal have been studied during propagation within an axial gas jet. The effects of nozzle shape, nozzle diameter, and variations in jet velocity, temperature and gas composition have been investigated. At high flow velocities of an air jet, divergence of the ultrasonic beam was observed. This was attributed to the effects of refraction, caused by increased acoustic velocities in the direction of the flow. An effective waveguide was also demonstrated by cooling the air jet to below ambient temperatures, so that the acoustic velocity in the air jet was lower than that in the surrounding atmosphere. This could also be achieved by using carbon dioxide mixed with air, whereas the use of helium led to increased divergence. The result is likely to be of use in air-coupled ultrasonic materials inspection.

Changes in cortical and striatal neurons predict behavioral and electrophysiological abnormalities in a transgenic murine model of Huntington's disease

Neurons in Huntington's disease exhibit selective morphological and subcellular alterations in the striatum and cortex. The link between these neuronal changes and behavioral abnormalities is unclear. We investigated relationships between essential neuronal changes that predict motor impairment and possible involvement of the corticostriatal pathway in developing behavioral phenotypes. We therefore generated heterozygote mice expressing the N-terminal one-third of huntingtin with normal (CT18) or expanded (HD46, HD100) glutamine repeats. The HD mice exhibited motor deficits between 3 and 10 months. The age of onset depended on an expanded polyglutamine length; phenotype severity correlated with increasing age. Neuronal changes in the striatum (nuclear inclusions) preceded the onset of phenotype, whereas cortical changes, especially the accumulation of huntingtin in the nucleus and cytoplasm and the appearance of dysmorphic dendrites, predicted the onset and severity of behavioral deficits. Striatal neurons in the HD mice displayed altered responses to cortical stimulation and to activation by the excitotoxic agent NMDA. Application of NMDA increased intracellular Ca(2+) levels in HD100 neurons compared with wild-type neurons. Results suggest that motor deficits in Huntington's disease arise from cumulative morphological and physiological changes in neurons that impair corticostriatal circuitry.

Dead or alive: immunogenicity of human melanoma cells when presented by dendritic cells

Uveal melanoma is an aggressive malignancy with a poor prognosis despite current therapeutic intervention. These tumors have been shown to be antigenic because they express a number of melanoma-associated antigens and are therefore attractive targets for immunotherapy. Here, we investigated the immunogenicity of uveal melanoma cells that have undergone apoptosis and compared this with their necrotic or live counter-parts. The fate of the tumor antigens in these cells largely depends on their ability to be processed and phagocytosed by dendritic cells (DCs). Flow cytometric analysis shows that human DCs form conjugates more efficiently with dead uveal melanoma cells, and consequently these are effective stimuli of lymphocyte proliferation. However, only DCs pulsed with apoptotic cells were able to induce proliferation of CD8+ cytotoxic T cells and stimulate antigen-specific T cells. This study demonstrates for the first time that DCs derived from melanoma patients process and present antigens derived from both HLA-matched or HLA-mismatched human apoptotic tumor cells stimulating both CD4+ and CD8+ T cells. This approach may be important to the development of DC-based immunotherapies for melanoma.