Low intrinsic efficacy for G protein activation can explain the improved side effect profiles of new opioid agonists

Biased agonism at G protein-coupled receptors describes the phenomenon whereby some drugs can activate some downstream signaling activities to the relative exclusion of others. Descriptions of biased agonism focusing on the differential engagement of G proteins versus β-arrestins are commonly limited by the small response windows obtained in pathways that are not amplified or are less effectively coupled to receptor engagement, such as β-arrestin recruitment. At the μ-opioid receptor (MOR), G protein-biased ligands have been proposed to induce less constipation and respiratory depressant side effects than opioids commonly used to treat pain. However, it is unclear whether these improved safety profiles are due to a reduction in β-arrestin-mediated signaling or, alternatively, to their low intrinsic efficacy in all signaling pathways. Here, we systematically evaluated the most recent and promising MOR-biased ligands and assessed their pharmacological profile against existing opioid analgesics in assays not confounded by limited signal windows. We found that oliceridine, PZM21, and SR-17018 had low intrinsic efficacy. We also demonstrated a strong correlation between measures of efficacy for receptor activation, G protein coupling, and β-arrestin recruitment for all tested ligands. By measuring the antinociceptive and respiratory depressant effects of these ligands, we showed that the low intrinsic efficacy of opioid ligands can explain an improved side effect profile. Our results suggest a possible alternative mechanism underlying the improved therapeutic windows described for new opioid ligands, which should be taken into account for future descriptions of ligand action at this important therapeutic target.

Anomalous surface diffusion in nanoscale direct deposition processes

We report the first observation of anomalous diffusion in nanometer scale direct deposition processes utilizing dip-pen nanolithography (DPN). DPN permits quite general nanostructure patterns to be drawn on flat surfaces. Here we demonstrate experimentally, and discuss theoretically, the situation in which the molecular ink in DPN binds weakly to the surface. We observe, for the weak-binding case of 1-dodecylamine on mica, that anomalous diffusion occurs, leading to nearly fractal deposition patterns.

Integration of nanowire devices in out-of-plane geometry

We report the fabrication of arrays of single and multiple out-of-plane nanowire devices on a single substrate, an important step for the fabrication of novel three-dimensional devices and the integration of individually addressable nanowires onto current Si planar technology platforms. Vertical nanowire device fabrication can greatly increase device densities; however integrating such devices into arrays with registry to the substrate requires precise control over the number and position of the nanowires. Here we report the directed assembly of gold nanoparticle seeds into patterned arrays for the growth of nanowires using chemical recognition and electrophoretic methods. Chemical recognition provides highly reproducible control of the position and number of nanoparticles per pattern element and is shown to be in good agreement with a simple electrostatic model. Individually addressed out-of-plane, vapor-liquid-solid grown Ge nanowires with single and multiple nanowires per element are fabricated and electrically characterized.

Tapentadol shows lower intrinsic efficacy at µ receptor than morphine and oxycodone

Tapentadol is a centrally acting analgesic with a dual mechanism of action. It acts as an agonist at the µ receptor and inhibitor of noradrenaline reuptake. Clinical trials suggest similar analgesic efficacy of tapentadol, oxycodone, and morphine in acute and chronic pain. Given the limited information about the molecular actions of tapentadol at the µ receptor, we investigated the intrinsic efficacy of tapentadol and compared it with other opioids. β-chlornaltrexamine (β-CNA, 100 nM, 20 min) was used to deplete spare receptors in AtT20 cells stably transfected with human µ receptor wild-type (WT). Opioid-mediated changes in membrane potential were measured in real-time using a membrane potential-sensitive fluorescent dye. Using Black and Leff's operational model, intrinsic efficacy relative to DAMGO was calculated for each opioid. Tapentadol (0.05 ± 0.01) activated the GIRK channel with lesser intrinsic efficacy than morphine (0.17 ± 0.02) and oxycodone (0.16 ± 0.02). We further assessed the signaling of tapentadol in the common µ receptor variants (N40D and A6V) which are associated with altered receptor signaling. We found no difference in the response of tapentadol between these receptor variants.

Evaluating Opioid-Mediated Adenylyl Cyclase Inhibition in Live Cells Using a BRET-Based Assay

Quantitative measurement of receptor signaling by different ligands is important for understanding the mechanism of drug action and screening of drugs. Here, we describe a simple and cost-effective method of measuring adenylyl cyclase inhibition, one of the hallmarks of opioid receptor activation. The assay is based on bioluminescence resonance energy transfer (BRET) that involves transfection of a biosensor in human embryonic kidney (HEK)-293 cells stably transfected with μ-opioid receptor (μ receptor), enabling real-time measurement of cAMP levels.

Do gabapentin or pregabalin directly modulate the µ receptor?

BACKGROUND

Pregabalin and gabapentin improve neuropathic pain symptoms but there are emerging concerns regarding their misuse. This is more pronounced among patients with substance use disorder, particularly involving opioids. Co-ingestion of gabapentinoids with opioids is increasingly identified in opioid related deaths, however, the molecular mechanism behind this is still unclear. We have sought to determine whether pregabalin or gabapentin directly modulates acute μ receptor signaling, or μ receptor activation by morphine.

METHODS

The effects of pregabalin and gabapentin were assessed in HEK 293 cells stably transfected with the human μ receptor. Their effect on morphine induced hyperpolarization, cAMP production and ERK phosphorylation were studied using fluorescent-based membrane potential assay, bioluminescence based CAMYEL assay and ELISA assay, respectively. Pregabalin/gabapentin effects on morphine-induced hyperpolarization were also investigated in AtT20 cells.

RESULTS

Pregabalin or gabapentin (1 µM, 100 µM each) did not activate the µ receptor or affect K channel activation or ERK phosphorylation produced by morphine. Neither drug affected the desensitization of K channel activation produced by prolonged (30 min) application of morphine. Gabapentin (1 µM, 100 µM) and pregabalin (1 µM) did not affect inhibition of forskolin-stimulated cAMP production by morphine. However, pregabalin (100 µM) potentiated forskolin mediated cAMP production, although morphine still inhibited cAMP levels with a similar potency to control.

DISCUSSION

Pregabalin or gabapentin did not activate or modulate µ receptor signaling in three different assays. Our data do not support the hypothesis that gabapentin or pregabalin augment opioid effects through direct or allosteric modulation of the µ receptor. Pregabalin at a high concentration increases cAMP production independent of morphine. The mechanism of enhanced opioid-related harms from co-ingestion of pregabalin or gabapentin with opioids needs further investigation.

Job Satisfaction among School Teachers in Duwakot, Bhaktapur District, Nepal

Introduction: Job satisfaction is one of the determinant factors for professionals. The job satisfaction concerning school teachers reflects their strong motivation towards their job. This study aimed to measure the job satisfaction among teachers of Government and Private schools of  Changu Narayan Municipality. Methods: A cross-sectional study was done at seven government and five private schools of wards no. 1 and 2 of Changu Narayan Municipality Bhaktapur District, Nepal over one month (20th April - 19th May 2021). Schools of Changu Narayan Municipality Ward No. 1 and 2 were purposively selected. The data was collected through validated questionnaire on Job Description Index (JDI)8 which consists of 17 domains. Data were entered in Excel and data analysis was done in SPSS version 20. Results: The overall job satisfaction was 65.77±11.52 which indicates that the majority of teachers were highly satisfied with their job. Conclusion:  The findings of this study indicate job satisfaction among  school level teachers was satisfied in their occupation especially in teaching profession. The domain sources of job satisfaction in school teachers appear to be work itself, coworker, relationship with students and sense of achievement. Whereas motivation in profession is most likely to be less job satisfaction among Government and Private schools.

Addressing Domestic Violence in Antenatal Care Environments in Nepal (ADVANCE) - study protocol for a randomized controlled trial evaluating a video intervention on domestic violence among pregnant women

BACKGROUND

Domestic violence (DV) prior to, and during pregnancy is associated with increased risks for morbidity and mortality. As pregnant women routinely attend antenatal care this environment can be used to offer support to women experiencing DV. We have developed a video intervention that focuses on the use of behavioral coping strategies, particularly regarding disclosure of DV experiences. The effectiveness of this intervention will be evaluated through a randomized controlled trial (RCT) and a concurrent process evaluation.

METHODS

All pregnant women between 12-22 weeks of gestation attending routine antenatal care at two tertiary level hospitals in Nepal are invited to participate. DV is measured using the Nepalese version of the Abuse Assessment Screen (N-AAS). Additionally, we measure participants' mental health, use of coping strategies, physical activity, and food security through a Color-coded Audio Computer Assisted Self Interview (C-ACASI). Irrespective of DV status, women are randomized into the intervention or control arm using a computer-generated randomization program. The intervention arm views a short video providing information on DV, safety improving actions women can take with an emphasis on disclosing the violence to a trusted person along with utilizing helplines available in Nepal. The control group watches a video on maintaining a healthy pregnancy and when to seek healthcare. The primary outcome is the proportion of women disclosing their DV status to someone. Secondary outcomes are symptoms of anxiety and depression, coping strategies, the use of safety measures and attitudes towards acceptance of abuse. Follow-up is conducted after 32 weeks of gestation, where both the intervention and control group participants view the intervention video after completing the follow-up questionnaire. Additionally, a mixed methods process evaluation of the intervention will be carried out to explore factors influencing the acceptability of the intervention and the disclosure of DV, including a review of project documents, individual interviews, and focus group discussions with members of the research team, healthcare providers, and participants.

DISCUSSION

This study will provide evidence on whether pregnant women attending regular antenatal visits can enhance their safety by disclosing their experiences of violence to a trusted person after receiving a video intervention.

TRIAL REGISTRATION

The study is registered in ClinicalTrial.gov with identifier NCT05199935.

Periodontitis and Diabetes: How Well the Patients have Knowledge about the Established Interrelationship?

Background Type 2 diabetes is an escalating health problem in Nepal and it holds a strong bidirectional Inter relationship with periodontitis. However, lack of its knowledge and motivation among patients may deteriorate and complicate their condition. Objective To assess knowledge among general population regarding the relation between diabetes and periodontitis and to evaluate the role of dentists and physicians in suggesting the diabetic patients for oral health care. Method A cross-sectional study was conducted among the patients visiting Department of Periodontics, Gandaki Medical College. A total 422 patients were interviewed using a set of pretested questionnaire and at the end they were counselled about the impact of diabetes mellitus on periodontal status and vice versa. Result Majority of the patients 257 (60.9%) had no idea about the interrelation between periodontitis and diabetes mellitus. Almost all the patients 363 (86.02%) assumed that poor oral health cannot increase the risk of developing diabetes and amongst those who had knowledge about this relation, the major source of information was their diabetic friends and relatives 46 (10.9%) and other sources such as syllabus 46 (10.9%). Only handful of patients 30 (7.10%) were informed about the relation by their dentist. Ironically, none of them were provided information about the interrelation by their treating physician. Conclusion Overall, only few participants had knowledge about the bidirectional relation between periodontitis and diabetes. Hence, our findings support the greater need for more targeted and specific health education along with close collaboration between dentists and physicians.

Vaginal Atresia with Cervical Agenesis, a Rare Congenital Malformation

Congenital vaginal atresia and cervical agenesis is a rare congenital abnormality of the female genital tract. Here we report a case of 15-year old girl with primary amenorrhea with hematometra, presented with lower abdominal mass. She was symptomatic since 5 months and visited local hospital after 4 months of onset of her symptoms when it became severe, where diagnostic laparotomy was performed for suspected Adnexal mass. Intraoperatively adnexal mass was adhered with and extended up to the uterus with 16 weeks size of uterus. Abdomen was closed without any further intervention and was referred to higher center for needful. When she presented to Kathmandu Model Hospital, she was asymptomatic on her 5th post-operative day of laparotomy. We planned for surgical intervention after examination and investigation. Drainage with vaginoplasty with amnion graft with placement of mould was done.

Assessing Health Status of Khanigaun Village Development Committee in Nuwakot District of Nepal

BACKGROUND

Assessing health status is crucial to understand the level of health in the community. Maternal health, child health and behavioral practice on diseases are key issues to assess health status of a community in Nepal. Nationwide surveys and literature suggest that there is improvement in health status of Nepalese community. Thus, the aim of this study was to assess general health status of Khanigaun VDC of Nepal and compare it with regional and national status.

METHODS

A descriptive cross-sectional study was undertaken using semi-structured questionnaire, interview and observation methods. Simple random sampling was done to conduct household survey among 346 (30%) households. Ethical approval was taken from Nepal Health Research Council, Ethical Review Board Results: General Fertility Rate (GFR) of the VDC was found 69.15 per 1000 Women. Literacy rate of the VDC was 71.14% and 74.92% of households depended on agriculture for income. The major health problem of the community was diarrhea followed by unknown fever and respiratory problems. More than 50% of women breastfed their children only up to the age of one year. Contraceptive prevalence rate was 72% and more than two third of women were found to be have delivered their most recent baby at home. It was found that 31% of newborn were born underweight and measles immunization coverage was 89%. After need identification and prioritization, Micro Health Project (MHP) was conducted to create health related awareness among the people through demonstration and exhibition.

CONCLUSIONS

Regular health status assessment of a community people that ultimately helps to plan the health programs and services accordingly.

A Study on Variations of Nutrient Foramen of Humerus with its Clinical Implications

Background Nutrient foramen is an opening into shaft of humerus which gives passage to the blood vessels of medullary cavity. The knowledge of nutrient foramen is important in surgical procedures like bone grafting and more recently in microsurgical vascularized bone transplantation. Objective To determine the number, location and direction of nutrient foramen and whether the nutrient foramens obey the rule of ossification, that is directed away from the growing end of the bone or not. Method The present study consisted of 253 (108 right and 145 left) dried humeri excluding any fracture or pathological abnormalities during the period of 15th December 2014 - 14th February 2015. Number and direction of nutrient foramen was observed in each humerus. Location of nutrient foramen in relation with surfaces and zones of humeri was determined. Result It has been observed that 60.87% of the humeri had a single nutrient foramen, 28.85% double foramen, 6.32% triple foramen and 1.98% of humeri had four nutrient foramina where as 1.98% humeri did not have any nutrient foramina. It was concluded that the majority (88.86%) of the nutrient foramina were present on the antero-medial surface, 6.52% on the anterolateral surface and 4.62% on the posterior surface of the shaft of humeri. It was also concluded that most (94.84%) of the foramina present in the zone II followed by zone III (4.62%) then by zone I (0.54%). All foramina were directed toward the lower end of humeri. Conclusion By knowing the number and location of the nutrient foramina in humerus would be useful in preventing intra-operative injury of nutrient artery during orthopedic, plastic and reconstructive surgery and will also be relevant in medico legal practice.