Neuromedin B-Expressing Neurons in the Retrotrapezoid Nucleus Regulate Respiratory Homeostasis and Promote Stable Breathing in Adult Mice.

Respiratory chemoreceptor activity encoding arterial Pco2 and Po2 is a critical determinant of ventilation. Currently, the relative importance of several putative chemoreceptor mechanisms for maintaining eupneic breathing and respiratory homeostasis is debated. Transcriptomic and anatomic evidence suggests that bombesin-related peptide Neuromedin-B (Nmb) expression identifies chemoreceptor neurons in the retrotrapezoid nucleus (RTN) that mediate the hypercapnic ventilatory response, but functional support is missing. In this study, we generated a transgenic Nmb-Cre mouse and used Cre-dependent cell ablation and optogenetics to test the hypothesis that RTN Nmb neurons are necessary for the CO2-dependent drive to breathe in adult male and female mice. Selective ablation of ∼95% of RTN Nmb neurons causes compensated respiratory acidosis because of alveolar hypoventilation, as well as profound breathing instability and respiratory-related sleep disruption. Following RTN Nmb lesion, mice were hypoxemic at rest and were prone to severe apneas during hyperoxia, suggesting that oxygen-sensitive mechanisms, presumably the peripheral chemoreceptors, compensate for the loss of RTN Nmb neurons. Interestingly, ventilation following RTN Nmb -lesion was unresponsive to hypercapnia, but behavioral responses to CO2 (freezing and avoidance) and the hypoxia ventilatory response were preserved. Neuroanatomical mapping shows that RTN Nmb neurons are highly collateralized and innervate the respiratory-related centers in the pons and medulla with a strong ipsilateral preference. Together, this evidence suggests that RTN Nmb neurons are dedicated to the respiratory effects of arterial Pco2/pH and maintain respiratory homeostasis in intact conditions and suggest that malfunction of these neurons could underlie the etiology of certain forms of sleep-disordered breathing in humans.SIGNIFICANCE STATEMENT Respiratory chemoreceptors stimulate neural respiratory motor output to regulate arterial Pco2 and Po2, thereby maintaining optimal gas exchange. Neurons in the retrotrapezoid nucleus (RTN) that express the bombesin-related peptide Neuromedin-B are proposed to be important in this process, but functional evidence has not been established. Here, we developed a transgenic mouse model and demonstrated that RTN neurons are fundamental for respiratory homeostasis and mediate the stimulatory effects of CO2 on breathing. Our functional and anatomic data indicate that Nmb-expressing RTN neurons are an integral component of the neural mechanisms that mediate CO2-dependent drive to breathe and maintain alveolar ventilation. This work highlights the importance of the interdependent and dynamic integration of CO2- and O2-sensing mechanisms in respiratory homeostasis of mammals.

Dietary interventions improve diabetic kidney disease, but not peripheral neuropathy, in a db/db mouse model of type 2 diabetes.

Patients with type 2 diabetes often develop the microvascular complications of diabetic kidney disease (DKD) and diabetic peripheral neuropathy (DPN), which decrease quality of life and increase mortality. Unfortunately, treatment options for DKD and DPN are limited. Lifestyle interventions, such as changes to diet, have been proposed as non-pharmacological treatment options for preventing or improving DKD and DPN. However, there are no reported studies simultaneously evaluating the therapeutic efficacy of varying dietary interventions in a type 2 diabetes mouse model of both DKD and DPN. Therefore, we compared the efficacy of a 12-week regimen of three dietary interventions, low carbohydrate, caloric restriction, and alternate day fasting, for preventing complications in a db/db type 2 diabetes mouse model by performing metabolic, DKD, and DPN phenotyping. All three dietary interventions promoted weight loss, ameliorated glycemic status, and improved DKD, but did not impact percent fat mass and DPN. Multiple regression analysis identified a negative correlation between fat mass and motor nerve conduction velocity. Collectively, our data indicate that these three dietary interventions improved weight and glycemic status and alleviated DKD but not DPN. Moreover, diets that decrease fat mass may be a promising non-pharmacological approach to improve DPN in type 2 diabetes given the negative correlation between fat mass and motor nerve conduction velocity.

Single-cell RNA-seq uncovers novel metabolic functions of Schwann cells beyond myelination.

Schwann cells (SCs) support peripheral nerves under homeostatic conditions, independent of myelination, and contribute to damage in prediabetic peripheral neuropathy (PN). Here, we used single-cell RNA sequencing to characterize the transcriptional profiles and intercellular communication of SCs in the nerve microenvironment using the high-fat diet-fed mouse, which mimics human prediabetes and neuropathy. We identified four major SC clusters, myelinating, nonmyelinating, immature, and repair in healthy and neuropathic nerves, in addition to a distinct cluster of nerve macrophages. Myelinating SCs acquired a unique transcriptional profile, beyond myelination, in response to metabolic stress. Mapping SC intercellular communication identified a shift in communication, centered on immune response and trophic support pathways, which primarily impacted nonmyelinating SCs. Validation analyses revealed that neuropathic SCs become pro-inflammatory and insulin resistant under prediabetic conditions. Overall, our study offers a unique resource for interrogating SC function, communication, and signaling in nerve pathophysiology to help inform SC-specific therapies.

Experiences from the Philippine grassroots: impact of strengthening primary care systems on health worker satisfaction and intention to stay.

BACKGROUND: Inequities in health access and outcomes persist in low- and middle-income countries. While strengthening primary care is integral in improving patient outcomes, primary care networks remain undervalued, underfunded, and underdeveloped in many LMICs such as the Philippines. This paper underscores the value of strengthening primary care system interventions in LMICs by examining their impact on job satisfaction and intention to stay among healthcare workers in the Philippines. METHODS: This study was conducted in urban, rural, and remote settings in the Philippines. A total of 36 urban, 54 rural, and 117 remote healthcare workers participated in the study. Respondents comprised all family physicians, nurses, midwives, community health workers, and staff involved in the delivery of primary care services from the sites. A questionnaire examining job satisfaction (motivators) and dissatisfaction (hygiene) factors was distributed to healthcare workers before and after system interventions were introduced across sites. Interventions included the introduction of performance-based incentives, the adoption of electronic health records, and the enhancement of diagnostic and pharmaceutical capabilities over a 1-year period. A Wilcoxon signed-rank test and a McNemar's chi-square test were then conducted to compare pre- and post-intervention experiences for each setting. RESULTS: Among the factors examined, results revealed a significant improvement in perceived compensation fairness among urban (p = 0.001) and rural (p = 0.016) providers. The rural workforce also reported a significant improvement in medicine access (p = 0.012) post-intervention. Job motivation and turnover intention were sustained in urban and rural settings between periods. Despite the interventions introduced, a decline in perceptions towards supply accessibility, job security, and most items classified as job motivators was reported among remote providers. Paralleling this decline, remote primary care providers with the intent to stay dropped from 93% at baseline to 75% at endline (p < 0.001). CONCLUSION: The impact of strengthening primary care on health workforce satisfaction and turnover intention varied across urban, rural, and remote settings. While select interventions such as improving compensation were promising for better-supported settings, the immediate impact of these interventions was inadequate in offsetting the infrastructural and staffing gaps experienced in disadvantaged areas. Unless these problems are comprehensively addressed, satisfaction will remain low, workforce attrition will persist as a problem, and marginalized communities will be underserved.

Nurses' strategies for overcoming barriers to fundamental nursing care in patients with COVID-19 caused by infection with the SARS-COV-2 virus: Results from the 'COVID-NURSE' survey.

AIMS: To identify strategies used by registered nurses and non-registered nursing care staff in overcoming barriers when providing fundamental nursing care for non-invasively ventilated inpatients with COVID-19. DESIGN: Online survey with open-ended questions to collect qualitative data. METHODS: In August 2020, we asked UK-based nursing staff to describe any strategies they employed to overcome barriers to delivering care in 15 fundamental nursing care categories when providing care to non-invasively ventilated patients with COVID-19. We analysed data using Framework Analysis. RESULTS: A total of 1062 nurses consented to participate in our survey. We derived four themes. 1) Communication behaviours included adapting verbal and non-verbal communication with patients, using information technology to enable patients' significant others to communicate with staff and patients, and establishing clear information-sharing methods with other staff. 2) Organizing care required clustering interventions, carefully managing supplies, encouraging patient self-care and using 'runners' and interdisciplinary input. 3) Addressing patients' well-being and values required spending time with patients, acting in loco familiae, providing access to psychological and spiritual support, obtaining information about patients' wishes early on and providing privacy and comforting/meaningful items. 4) Management and leadership behaviours included training, timely provision of pandemic information, psychological support, team huddles and facilitating regular breaks. CONCLUSIONS: Our respondents identified multiple strategies in four main areas of clinical practice. Management and leadership are crucial to both fundamental care delivery and the well-being of nurses during pandemics. Grouping strategies into these areas of action may assist nurses and leaders to prepare for pandemic nursing. IMPACT: As these strategies are unlikely to be exclusive to the COVID-19 pandemic, their global dissemination may improve patient experience and help nurses deliver fundamental care when planning pandemic nursing. However, their effectiveness is unknown. Therefore, we are currently evaluating these strategies in a cluster randomized controlled trial.

Obesity-induced neuroinflammation and cognitive impairment in young adult versus middle-aged mice.

BACKGROUND: Obesity rates are increasing worldwide. Obesity leads to many complications, including predisposing individuals to the development of cognitive impairment as they age. Immune dysregulation, including inflammaging (e.g., increased circulating cytokines) and immunosenescence (declining immune system function), commonly occur in obesity and aging and may impact cognitive impairment. As such, immune system changes across the lifespan may impact the effects of obesity on neuroinflammation and associated cognitive impairment. However, the role of age in obesity-induced neuroinflammation and cognitive impairment is unclear. To further define this putative relationship, the current study examined metabolic and inflammatory profiles, along with cognitive changes using a high-fat diet (HFD) mouse model of obesity. RESULTS: First, HFD promoted age-related changes in hippocampal gene expression. Given this early HFD-induced aging phenotype, we fed HFD to young adult and middle-aged mice to determine the effect of age on inflammatory responses, metabolic profile, and cognitive function. As anticipated, HFD caused a dysmetabolic phenotype in both age groups. However, older age exacerbated HFD cognitive and neuroinflammatory changes, with a bi-directional regulation of hippocampal inflammatory gene expression. CONCLUSIONS: Collectively, these data indicate that HFD promotes an early aging phenotype in the brain, which is suggestive of inflammaging and immunosenescence. Furthermore, age significantly compounded the impact of HFD on cognitive outcomes and on the regulation of neuroinflammatory programs in the brain.

Fundamental nursing care in patients with the SARS-CoV-2 virus: results from the 'COVID-NURSE' mixed methods survey into nurses' experiences of missed care and barriers to care.

BACKGROUND: Patient experience of nursing care is associated with safety, care quality, treatment outcomes, costs and service use. Effective nursing care includes meeting patients' fundamental physical, relational and psychosocial needs, which may be compromised by the challenges of SARS-CoV-2. No evidence-based nursing guidelines exist for patients with SARS-CoV-2. We report work to develop such a guideline. Our aim was to identify views and experiences of nursing staff on necessary nursing care for inpatients with SARS-CoV-2 (not invasively ventilated) that is omitted or delayed (missed care) and any barriers to this care. METHODS: We conducted an online mixed methods survey structured according to the Fundamentals of Care Framework. We recruited a convenience sample of UK-based nursing staff who had nursed inpatients with SARS-CoV-2 not invasively ventilated. We asked respondents to rate how well they were able to meet the needs of SARS-CoV-2 patients, compared to non-SARS-CoV-2 patients, in 15 care categories; select from a list of barriers to care; and describe examples of missed care and barriers to care. We analysed quantitative data descriptively and qualitative data using Framework Analysis, integrating data in side-by-side comparison tables. RESULTS: Of 1062 respondents, the majority rated mobility, talking and listening, non-verbal communication, communicating with significant others, and emotional wellbeing as worse for patients with SARS-CoV-2. Eight barriers were ranked within the top five in at least one of the three care areas. These were (in rank order): wearing Personal Protective Equipment, the severity of patients' conditions, inability to take items in and out of isolation rooms without donning and doffing Personal Protective Equipment, lack of time to spend with patients, lack of presence from specialised services e.g. physiotherapists, lack of knowledge about SARS-CoV-2, insufficient stock, and reluctance to spend time with patients for fear of catching SARS-CoV-2. CONCLUSIONS: Our respondents identified nursing care areas likely to be missed for patients with SARS-CoV-2, and barriers to delivering care. We are currently evaluating a guideline of nursing strategies to address these barriers, which are unlikely to be exclusive to this pandemic or the environments represented by our respondents. Our results should, therefore, be incorporated into global pandemic planning.

The Divergent Roles of Dietary Saturated and Monounsaturated Fatty Acids on Nerve Function in Murine Models of Obesity.

Neuropathy is the most common complication of prediabetes and diabetes and presents as distal-to-proximal loss of peripheral nerve function in the lower extremities. Neuropathy progression and disease severity in prediabetes and diabetes correlates with dyslipidemia in man and murine models of disease. Dyslipidemia is characterized by elevated levels of circulating saturated fatty acids (SFAs) that associate with the progression of neuropathy. Increased intake of monounsaturated fatty acid (MUFA)-rich diets confers metabolic health benefits; however, the impact of fatty acid saturation in neuropathy is unknown. This study examines the differential effect of SFAs and MUFAs on the development of neuropathy and the molecular mechanisms underlying the progression of the complication. Male mice Mus musculus fed a high-fat diet rich in SFAs developed robust peripheral neuropathy. This neuropathy was completely reversed by switching the mice from the SFA-rich high-fat diet to a MUFA-rich high-fat diet; nerve conduction velocities and intraepidermal nerve fiber density were restored. A MUFA oleate also prevented the impairment of mitochondrial transport and protected mitochondrial membrane potential in cultured sensory neurons treated with mixtures of oleate and the SFA palmitate. Moreover, oleate also preserved intracellular ATP levels, prevented apoptosis induced by palmitate treatment, and promoted lipid droplet formation in sensory neurons, suggesting that lipid droplets protect sensory neurons from lipotoxicity. Together, these results suggest that MUFAs reverse the progression of neuropathy by protecting mitochondrial function and transport through the formation of intracellular lipid droplets in sensory neurons.SIGNIFICANCE STATEMENT There is a global epidemic of prediabetes and diabetes, disorders that represent a continuum of metabolic disturbances in lipid and glucose metabolism. In the United States, 80 million individuals have prediabetes and 30 million have diabetes. Neuropathy is the most common complication of both disorders, carries a high morbidity, and, despite its prevalence, has no treatments. We report that dietary intervention with monounsaturated fatty acids reverses the progression of neuropathy and restores nerve function in high-fat diet-fed murine models of peripheral neuropathy. Furthermore, the addition of the monounsaturated fatty acid oleate to sensory neurons cultured under diabetic conditions shows that oleate prevents impairment of mitochondrial transport and mitochondrial dysfunction through a mechanism involving formation of axonal lipid droplets.

Reducing fetal origins of childhood obesity through maternal smoking cessation during pregnancy: an intervention study.

Rapid infant weight gain predicts childhood obesity. We aimed to estimate effect size and identify critical timing for intervention-assisted smoking cessation during pregnancy to impact infant weight gain. We followed 25 mother-infant dyads in the UB Pregnancy and Smoking Cessation Study (Buffalo, NY, USA). Maternal smoking status was biochemically verified and monitored through pregnancy. Birth weight and length were extracted from birth records. Research staff measured infant weight and length at 2 weeks and monthly from 1 to 12 months of age. Mixed models were used to fit infant BMI-for-age z-score (ZBMI) trajectories. We found infants of quitters had lower ZBMI gain from birth to 12 months (mean ± SD, 1.13 ± 1.16) than infants of persistent smokers (2.34 ± 1.40; p = 0.035), with Cohen's d effect size being large (0.96). The infant ZBMI gain from birth to 12 months was low (<0.47) if smoking cessation was initiated between 15 and 27 weeks of pregnancy, but started to increase if quitting at 28 weeks (0.65) and accelerated with time (e.g., 3.16 if quitting at 36 weeks). We concluded maternal smoking cessation during pregnancy may reduce fetal origins of obesity through reducing infant weight gain, especially if quitting smoking by 27 weeks of pregnancy.