Amiodarone Alters Cholesterol Biosynthesis through Tissue-Dependent Inhibition of Emopamil Binding Protein and Dehydrocholesterol Reductase 24

Amiodarone is prescribed for the treatment and prevention of irregular heartbeats. Although effective in clinical practice, the long-term use of amiodarone has many unwanted side effects, including cardiac, pulmonary, hepatic, and neurological toxicities. Our objective was to elucidate effects of amiodarone exposure on the cholesterol metabolism in cultured neuronal and non-neuronal cells and in individuals taking amiodarone. We observed that amiodarone increases distinct cholesterol precursors in different cell types in a dose-dependent manner. In liver and kidney cell lines, amiodarone causes increase in desmosterol levels, and in primary cortical neurons and astrocytes, amiodarone increases zymosterol, zymostenol, and 8-dehydrocholesterol (8-DHC). We conclude that amiodarone inhibits two enzymes in the pathway, emopamil binding protein (EBP) and dehydrocholesterol reductase 24 (DHCR24). Cortical neurons and astrocytes are more sensitive to amiodarone than liver and kidney cell lines. We confirmed the inhibition of EBP enzyme by analyzing the sterol intermediates in EBP-deficient Neuro2a cells versus amiodarone-treated control Neuro2a cells. To determine if the cell culture experiments have clinical relevance, we analyzed serum samples from amiodarone users. We found that in patient serum samples containing detectable amount of amiodarone there are elevated levels of the sterol precursors zymosterol, 8-DHC, and desmosterol. This study illustrates the need for close monitoring of blood biochemistry during prolonged amiodarone use to minimize the risk of side effects.

Maternal cariprazine exposure inhibits embryonic and postnatal brain cholesterol biosynthesis

Cariprazine (CAR) is a strong inhibitor of the Dhcr7 enzyme, the last enzyme in the cholesterol biosynthesis pathway. We assessed the effects of CAR on maternally exposed Dhcr7^+/- and wild-type mouse offspring, and tested the biochemical effects of CAR in human serum samples. Dhcr7^+/- and wild-type time-pregnant mice were exposed to vehicle or 0.2 mg/kg CAR from E12 to E19. Levels of CAR, CAR metabolites, sterols, and oxysterols were measured in the brain of maternally exposed offspring at various time points using LC-MS/MS. Embryonic exposure to CAR significantly increased levels of 7-DHC in all organs of exposed embryos, with a particularly strong effect in the brain. Detectable levels of CAR and elevated 7-DHC were observed in the brain of newborn pups 14 days after drug exposure. In addition, CAR altered sterol metabolism in all animals analyzed, with the strongest effect on the brain of Dhcr7^+/- pups born to Dhcr7^+/- dams. Furthermore, CAR elevated toxic oxysterols in the brain of maternally exposed Dhcr7^+/- offspring to levels approaching those seen in a mouse model of Smith-Lemli-Opitz syndrome. Finally, we observed that patients taking CAR have elevated 7-DHC in their serum. In summary, maternal DHCR7 heterozygosity, combined with offspring DHCR7 heterozygosity might represent a vulnerability factor to medications that interfere with sterol biosynthesis. Due to the conserved sterol biosynthesis between mice and humans, we suggest that the 1-3% of patient population with single-allele DHCR7 mutations might not be ideal candidates for CAR use, especially if they are nursing, pregnant or plan to become pregnant.

TECRA® Unique™ Test for Rapid Detection of Salmonella in Food: Collaborative Study

The TECRA® Unique™ Salmonella test uses the principle of immunoenrichment to allow rapid detection of Salmonellae in food. A collaborative study was conducted to compare the TECRA Salmonella Unique test with the reference culture method given in the U.S. Food and Drug Administration's Bacteriological Analytical Manual. Three food types (milk powder, pepper, and soy flour) were analyzed in Australia and 2 food types (milk chocolate and dried egg) were analyzed in the United States. Forty-one collaborators participated in the study. For each of the 5 foods at each of the 3 levels, a comparison showed no significant differences (p ≥ 0.05) in the proportion of positive test samples for Unique and that for the reference method using the Chi-square test for independence with continuity correction.

Factors Affecting Discharge Disposition After Primary Simultaneous Bilateral Joint Arthroplasty

BACKGROUND

Predicting discharge destination following total joint arthroplasty (TJA) is important, as discharge destination has major implications for post-operative costs, clinical outcomes, and readmissions. Few studies have looked at factors affecting discharge destination for patients following primary simultaneous bilateral total joint arthroplasty.

QUESTIONS/PURPOSES

The purpose of this study was to describe clinical and social factors that relate to a discharge to home versus rehabilitation facility (RF) for patients after primary simultaneous bilateral total hip arthroplasty (PSBTHA) or primary simultaneous bilateral total knee arthroplasty (PSBTKA).

METHODS

The inclusion criteria for this retrospective cohort study were all patients after PSBTHA or PSBTKA at a metropolitan orthopedic specialty hospital between February 1, 2016, and March 31, 2018. Exclusion criteria were revisions, differing weight-bearing status, bed-rest orders, and non-standard hip precautions. Social and clinical demographic data were collected. Multiple regression analysis was conducted to determine which factors related most to discharge plan.

RESULTS

Of 253 PSBTHA patients, 153 were discharged home and 100 to an RF. Regression analysis found a posterolateral approach to be the only significant factor associated with an RF discharge. Of 619 PSBTKA patients, 136 were discharged home and 483 to RF. Increased body mass index and older age increased the likelihood of discharge to an RF. Patients with an adductor-only nerve block were more likely to be sent to RF.

CONCLUSION

These findings shed light on the variables that contribute to discharge destination after PSBTHA and PSBTKA. Such information allows for safe pre-operative discharge planning and assists with discharge to the appropriate level of patient care. Future studies might investigate the effect of surgeon experience, surgical technique, and pre-operative discussion with a physical therapist on the discharge disposition of patients undergoing bilateral total joint arthroplasty.

Cholesterol Biosynthesis and Uptake in Developing Neurons

Brain cholesterol biosynthesis, a separate and distinct process from whole-body cholesterol homeostasis, starts during embryonic development. To gain a better understanding of the neuronal and glial contributions to the brain cholesterol pool, we studied this process in control, Dhcr7^-/-, and Dhcr24^-/- cell cultures. Our LC-MS/MS method allowed us to measure several different sterol intermediates and cholesterol during neuronal differentiation. We found that developing cortical neurons rely on endogenous cholesterol synthesis and utilize ApoE-complexed cholesterol and sterol precursors from their surroundings. Both developing neurons and astrocytes release cholesterol into their local environment. Our studies also uncovered that developing neurons produced significantly higher amounts of cholesterol per cell than the astrocytes. Finally, we established that both neurons and astroglia preferentially use the Bloch sterol biosynthesis pathway, where desmosterol is the immediate precursor to cholesterol. Overall, our studies suggest that endogenous sterol synthesis in developing neurons is a critical and complexly regulated homeostatic process during brain development.

Implications of Space Suit Injury Risk for Developing Computational Performance Models

INTRODUCTION: Although a space suit is a technological feat sustaining human life outside the spacecraft, working in the space suit environment can lead to musculotendon and soft tissue injuries in astronauts. In this literature review, we consider the injury risk mechanisms for human-space suit interactions. We first present a review of space suit injury risk founded in empirical, statistical, and experimental studies. We then review efforts in computational modeling of a human and space suit. As the interpretation of models for injury risk has not previously been defined, a review is presented of biomechanical considerations of injury risk to the tissue and joints based on previously observed space suit injuries. A review of risk assessment in occupational health in the workplace is then presented, an adjacent area that informs relevant measures of consideration for human-space suit applications. Finally, we discuss how the work-to-date can inform continued efforts in minimizing risk of musculoskeletal injury to the human when using a space suit. From the literature, this review concludes space suits cause biomechanical alterations, inducing musculoskeletal injury. Combining occupational health kinematic constraints with computational models could enable a trade space evaluation on space suited biomechanics to reduce risk mechanisms. Future work, though, is required to enable computational models to be predictive of individual injury risk. Our findings show there are significant gaps in our current knowledge on tissue injuries that preclude biomechanical models from being used directly as an injury risk assessment model. This review identifies how risk factor monitoring and modeling will enable improved space suit design and evaluation.Stirling L, Arezes P, Anderson A. Implications of space suit injury risk for developing computational performance models. Aerosp Med Hum Perform. 2019; 90(6):553-565.

VU0810464, a non-urea G protein-gated inwardly rectifying K+ (Kir 3/GIRK) channel activator, exhibits enhanced selectivity for neuronal Kir 3 channels and reduces stress-induced hyperthermia in mice

BACKGROUND AND PURPOSE

G protein-gated inwardly rectifying K⁺ (K_ir 3) channels moderate the activity of excitable cells and have been implicated in neurological disorders and cardiac arrhythmias. Most neuronal K_ir 3 channels consist of K_ir 3.1 and K_ir 3.2 subtypes, while cardiac K_ir 3 channels consist of K_ir 3.1 and K_ir 3.4 subtypes. Previously, we identified a family of urea-containing K_ir 3 channel activators, but these molecules exhibit suboptimal pharmacokinetic properties and modest selectivity for K_ir 3.1/3.2 relative to K_ir 3.1/3.4 channels. Here, we characterize a non-urea activator, VU0810464, which displays nanomolar potency as a K_ir 3.1/3.2 activator, improved selectivity for neuronal K_ir 3 channels, and improved brain penetration.

EXPERIMENTAL APPROACH

We used whole-cell electrophysiology to measure the efficacy and potency of VU0810464 in neurons and the selectivity of VU0810464 for neuronal and cardiac K_ir 3 channel subtypes. We tested VU0810464 in vivo in stress-induced hyperthermia and elevated plus maze paradigms. Parallel studies with ML297, the prototypical activator of K_ir 3.1-containing K_ir 3 channels, were performed to permit direct comparisons.

KEY RESULTS

VU0810464 and ML297 exhibited comparable efficacy and potency as neuronal K_ir 3 channel activators, but VU0810464 was more selective for neuronal K_ir 3 channels. VU0810464, like ML297, reduced stress-induced hyperthermia in a K_ir 3-dependent manner in mice. ML297, but not VU0810464, decreased anxiety-related behaviour as assessed with the elevated plus maze test.

CONCLUSION AND IMPLICATIONS

VU0810464 represents a new class of K_ir 3 channel activator with enhanced selectivity for K_ir 3.1/3.2 channels. VU0810464 may be useful for examining K_ir 3.1/3.2 channel contributions to complex behaviours and for probing the potential of K_ir 3 channel-dependent manipulations to treat neurological disorders.

Maternal aripiprazole exposure interacts with 7-dehydrocholesterol reductase mutations and alters embryonic neurodevelopment

Mutations in both copies in the gene encoding 7-dehydrocholesterol reductase (DHCR7) cause Smith-Lemli-Opitz Syndrome (SLOS), which is characterized by a toxic elevation in 7-dehydrocholesterol (7-DHC). Aripiprazole (ARI) exposure, independent of genetic mutations, also leads to elevation of 7-DHC. We investigated the combined effect of a single-copy Dhcr7^+/- mutation and maternal ARI exposure on the developing offspring brain. We generated a time-pregnant mouse model where WT and Dhcr7^+/- embryos were maternally exposed to ARI or vehicle (VEH) from E12 to E19 (5 mg/kg). Levels of cholesterol, its precursors, ARI and its metabolites were measured at P0. We found that ARI and its metabolites were transported across the placenta and reached the brain of offspring. Maternal ARI exposure led to decreased viability of embryos and increased 7-DHC levels, regardless of maternal or offspring Dhcr7 genotype. In addition, Dhcr7^+/- pups were more vulnerable to maternal ARI exposure than their WT littermates, and maternal Dhcr7^+/- genotype also exacerbated offspring response to ARI treatment. Finally, both 7-DHC levels and 7-DHC/cholesterol ratio is the highest in Dhcr7^+/- pups from Dhcr7^+/- mothers exposed to ARI, underscoring a potentially dangerous interaction between maternal genotype×embryonic genotype×treatment. Our findings have important clinical implications. SLOS patients should avoid drugs that increase 7-DHC levels such as ARI, trazodone and haloperidol. In addition, treatment with 7-DHC elevating substances might be potentially unsafe for the 1-1.5% of population with single-allele disruptions of the DHCR7 gene. Finally, prenatal and parental genetic testing for DHCR7 should be considered before prescribing sterol-interfering medications during pregnancy.

Engaging Men in Psychosocial Cancer Support

Background: Despite increasing rates of cancer survivorship, there is still evidence to suggest men are less likely to access information services, health services and cancer screening. Men may be more reticent to express their emotions in relation to health and specifically in relation to cancer; and so it is important to ensure that services offer different routes to inclusion. Maggie´s ( www.maggiescentres.org ) is an innovative, multidisciplinary, health professional led model of holistic supportive cancer care, widely regarded as an exemplar of best practice in cancer rehabilitation and supported self-management. In 2017 Maggie´s received 249,247 visits across their network of twenty-three centres in the UK, Hong Kong and Tokyo. One of the key challenges for Maggie´s and others is to develop sustainable, innovative and equitable approaches to supportive care. Aim: To explore whether male-specific facilitated support groups provide a constructive environment within which men can engage with health professional led holistic cancer services. Methods: Men (n=39) with a range of cancers (including curative and noncurative) from varied socioeconomic backgrounds, attending male-specific facilitated support groups at eight Maggie's Centres in the UK completed questionnaires to give feedback on the social, emotional, practical and informational support the groups aim to provide. A smaller subset of group members (n=12) participated in focus group discussions to capture themes about why men attend the groups. The group facilitators were interviewed to provide observations about the impact of the groups on both the participants and themselves. Results: Men in the facilitated support groups report high levels of satisfaction in relation to practical (94.8%), emotional (95.2%) and social (90.47%) and informational support (92.50%). Thematic analysis of the smaller subset of focus group data suggest reasons why men attend male-specific support groups including “reducing isolation and developing a sense of belonging”, “creating shared experience and understanding”, “safely expressing emotion”, “protecting loved ones from distress” and “use of male specific language and humor”. Conclusion: Globally, the supportive care needs of men affected by cancer are changing but the Maggie´s model of care offers valuable lessons that can be generalized across varied support settings to meet these emerging needs. The current study underlines the importance of engaging and supporting men throughout the cancer experience through the use of professionally facilitated support groups that discuss themes tailored to the challenges the men face and maximize the opportunity for acceptable social support. Further controlled longitudinal research is required to build on these findings.