Heart failure causes sleepless nights.

Cardiac dysfunction triggers immune-mediated loss of pineal gland melatonin release.

A tight squeeze: how do we make sense of small changes in microvascular diameter?

The brain is an energetically demanding tissue which, to function adequately, requires constant fine tuning of its supporting blood flow, and hence energy supply. Whilst blood flow was traditionally believed to be regulated only by vascular smooth muscle cells on arteries and arterioles supplying the brain, recent work has suggested a critical role for capillary pericytes, which are also contractile. This concept has evoked some controversy, especially over the relative contributions of arterioles and capillaries to the control of cerebral blood flow. Here we outline why pericytes are in a privileged position to control cerebral blood flow. First we discuss the evidence, and fundamental equations, which describe how the small starting diameter of capillaries, compared to upstream arterioles, confers a potentially greater control by capillary pericytes than by arterioles over total cerebral vascular resistance. Then we suggest that the faster time frame over which low branch order capillary pericytes dilate in response to local energy demands provides a niche role for pericytes to regulate blood flow compared to slower responding arterioles. Finally, we discuss the role of pericytes in capillary stalling, whereby pericyte contraction appears to facilitate a transient stall of circulating blood cells, exacerbating the effect of pericytes upon cerebral blood flow.

Plaque attack: Microglia have hard feelings toward amyloid-ß.

Classically, microglia recognize and internalize amyloid-ß (Aß) via it binding to cell surface receptors. In this issue of Neuron, Hu et al.1 report that microglia "feel" and internalize Aß plaques using the stiffness-sensing channel Piezo1. This could allow new approaches to treating Alzheimer's disease.

Healthy cardiac myocytes can decrease sympathetic hyperexcitability in the early stages of hypertension.

Sympathetic neurons are powerful drivers of cardiac excitability. In the early stages of hypertension, sympathetic hyperactivity is underpinned by down regulation of M current and increased activity of Cav2.2 that is associated with greater intracellular calcium transients and enhanced neurotransmission. Emerging evidence suggests that retrograde signaling from the myocyte itself can modulate synaptic plasticity. Here we tested the hypothesis that cross culturing healthy myocytes onto diseased stellate neurons could influence sympathetic excitability. We employed neuronal mono-cultures, co-cultures of neonatal ventricular myocytes and sympathetic stellate neurons, and mono-cultures of sympathetic neurons with media conditioned by myocytes from normal (Wistar) and pre-hypertensive (SHR) rats, which have heightened sympathetic responsiveness. Neuronal firing properties were measured by current-clamp as a proxy for neuronal excitability. SHR neurons had a maximum higher firing rate, and reduced rheobase compared to Wistar neurons. There was no difference in firing rate or other biophysical properties in Wistar neurons when they were co-cultured with healthy myocytes. However, the firing rate decreased, phenocopying the Wistar response when either healthy myocytes or media in which healthy myocytes were grown was cross-cultured with SHR neurons. This supports the idea of a paracrine signaling pathway from the healthy myocyte to the diseased neuron, which can act as a modulator of sympathetic excitability.

Post-Ganglionic Sympathetic Neurons can Directly Sense Raised Extracellular Na+ via SCN7a/Nax.

The relationship between dietary NaCl intake and high blood pressure is well-established, and occurs primarily through activation of the sympathetic nervous system. Nax, a Na+-sensitive Na+ channel, plays a pivotal role in driving sympathetic excitability, which is thought to originate from central regions controlling neural outflow. We investigated whether post-ganglionic sympathetic neurons from different ganglia innervating cardiac and vasculature tissue can also directly sense extracellular Na+. Using whole-cell patch clamp recordings we demonstrate that sympathetic neurons from three sympathetic ganglia (superior cervical, stellate and superior mesenteric/coeliac) respond to elevated extracellular NaCl concentration. In sympathetic stellate ganglia neurons, we established that the effect of NaCl was dose-dependent and independent of osmolarity, Cl- and membrane Ca2+ flux, and critically dependent on extracellular Na+ concentration. We show that Nax is expressed in sympathetic stellate ganglia neurons at a transcript and protein level using single-cell RNA-sequencing and immunohistochemistry respectively. Additionally, the response to NaCl was prevented by siRNA-mediated knockdown of Nax, but not by inhibition of other membrane Na+ pathways. Together, these results demonstrate that post-ganglionic sympathetic neurons are direct sensors of extracellular Na+ via Nax, which could contribute to sympathetic driven hypertension.

Hyperoxia evokes pericyte-mediated capillary constriction.

Oxygen supplementation is regularly prescribed to patients to treat or prevent hypoxia. However, excess oxygenation can lead to reduced cerebral blood flow (CBF) in healthy subjects and worsen the neurological outcome of critically ill patients. Most studies on the vascular effects of hyperoxia focus on arteries but there is no research on the effects on cerebral capillary pericytes, which are major regulators of CBF. Here, we used bright-field imaging of cerebral capillaries and modeling of CBF to show that hyperoxia (95% superfused O2) led to an increase in intracellular calcium level in pericytes and a significant capillary constriction, sufficient to cause an estimated 25% decrease in CBF. Although hyperoxia is reported to cause vascular smooth muscle cell contraction via generation of reactive oxygen species (ROS), endothelin-1 and 20-HETE, we found that increased cytosolic and mitochondrial ROS levels and endothelin release were not involved in the pericyte-mediated capillary constriction. However, a 20-HETE synthesis blocker greatly reduced the hyperoxia-evoked capillary constriction. Our findings establish pericytes as regulators of CBF in hyperoxia and 20-HETE synthesis as an oxygen sensor in CBF regulation. The results also provide a mechanism by which clinically administered oxygen can lead to a worse neurological outcome.

Abnormal Cyclic Nucleotide Signaling at the Outer Mitochondrial Membrane In Sympathetic Neurons During the Early Stages of Hypertension.

BACKGROUND: Disruption of cyclic nucleotide signaling in sympathetic postganglionic neurons contributes to impaired intracellular calcium handling (Ca2+) and the development of dysautonomia during the early stages of hypertension, although how this occurs is poorly understood. Emerging evidence supports the uncoupling of signalosomes in distinct cellular compartments involving cyclic nucleotide-sensitive PDEs (phosphodiesterases), which may underpin the autonomic phenotype in stellate neurons. METHODS: Using a combination of single-cell RNA sequencing together with Forster resonance energy transfer-based sensors to monitor cyclic adenosine 3',5'-monophosphate, PKA (protein kinase A)-dependent phosphorylation and cGMP (cyclic guanosine 3',5'-monophosphate), we tested the hypothesis that dysregulation occurs in a sub-family of PDEs in the cytosol and outer mitochondrial membrane of neurons from the stellate ganglion. RESULTS: PDE2A, 6D, 7A, 9A genes were highly expressed in young Wistar neurons and also conserved in neurons from spontaneously hypertensive rats (SHRs). In stellate neurons from prehypertensive SHRs, we found the levels of cyclic adenosine 3',5'-monophosphate and cGMP at the outer mitochondrial membrane were decreased compared with normal neurons. The reduced cyclic adenosine 3',5'-monophosphate response was due to the hydrolytic activity of overexpressed PDE2A2 located at the mitochondria. Normal cyclic adenosine 3',5'-monophosphate levels were re-established by inhibition of PDE2A. There was also a greater PKA-dependent phosphorylation in the cytosol and at the outer mitochondrial membrane in spontaneously hypertensive rat neurons, where this response was regulated by protein phosphatases. The cGMP response was only restored by inhibition of PDE6. CONCLUSIONS: When taken together, these results suggest that site-specific inhibition of PDE2A and PDE6D at the outer mitochondrial membrane may provide a therapeutic target to ameliorate cardiac sympathetic impairment during the onset of hypertension.

Molecular Correlates of Early Onset of Diabetic Cardiomyopathy: Possible Therapeutic Targets.

Diabetes mellitus (DM) is associated with mitochondrial dysfunction and oxidative stress that can lead to diabetic cardiomyopathy (DCM), which can often remain undetected until late stages of the disease. However, myocardial injury occurs before the onset of measurable cardiac dysfunction, although its molecular correlates are poorly understood. In this study, we made a DM rat induced by a high-fat diet combined with low and high doses of streptozotocin (STZ) to emulate pre and early DCM. RNA-sequencing analysis of ventricular tissue revealed a differential transcriptome profile and abnormal activation of pathways involved in fatty acid metabolism, oxidative phosphorylation, cardiac structure and function, insulin resistance, calcium signalling, apoptosis, and TNF signalling. Moreover, using high glucose-treated human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), we recapitulated the cardiac cellular phenotype of DM and identified several molecular correlates that may promote the development of DCM. In conclusion, we have developed an experimental framework to target pathways underlying the progression of DCM.

Downregulation of M Current Is Coupled to Membrane Excitability in Sympathetic Neurons Before the Onset of Hypertension.

Neurohumoral activation is an early hallmark of cardiovascular disease and contributes to the etiology of the pathophysiology. Stellectomy has reemerged as a positive therapeutic intervention to modify the progression of dysautonomia, although the biophysical properties underpinning abnormal activity of this ganglia are not fully understood in the initial stages of the disease. We investigated whether stellate ganglia neurons from prehypertensive SHRs (spontaneously hypertensive rats) are hyperactive and describe their electrophysiological phenotype guided by single-cell RNA sequencing, molecular biology, and perforated patch clamp to uncover the mechanism of abnormal excitability. We demonstrate the contribution of a plethora of ion channels, in particular inhibition of M current to stellate ganglia neuronal firing, and confirm the conservation of expression of key ion channel transcripts in human stellate ganglia. We show that hyperexcitability was curbed by M-current activators, nonselective sodium current blockers, or inhibition of Nav1.1-1.3, Nav1.6, or INaP. We conclude that reduced activity of M current contributes significantly to abnormal firing of stellate neurons, which, in part, contributes to the hyperexcitability from rats that have a predisposition to hypertension. Targeting these channels could provide a therapeutic opportunity to minimize the consequences of excessive sympathetic activation.

Transcriptional profiling of stellate ganglia from normotensive and spontaneously hypertensive rat strains.

The course of hypertension remains poorly understood, although impairment of the sympathetic nervous systems is thought to play a role in its aetiology. In this study, RNA-sequencing (RNAseq) was used to identify transcriptomal differences in the sympathetic stellate ganglia between 16-week-old normotensive Wistar rats and spontaneously hypertensive rats (SHR). Sequencing quality was assessed by FastQC and quasi-mapping rate by Salmon. Differential expression results were confirmed by real time reverse transcriptase Quantitative Polymerase Chain Reaction (qRT-PCR). RNAseq analysis was found to be predictive and representative of transcriptomal changes when compared to qRT-PCR by correlation analysis. Whether these changes underpin physiological sympathetic phenotypes associated with hypertension remains to be established, however this dataset identifies lead transcripts as a priori targets for further investigation.

RNA Sequencing Reveals Novel Transcripts from Sympathetic Stellate Ganglia During Cardiac Sympathetic Hyperactivity.

Cardiovascular disease is the most prevalent age-related illness worldwide, causing approximately 15 million deaths every year. Hypertension is central in determining cardiovascular risk and is a strong predictive indicator of morbidity and mortality; however, there remains an unmet clinical need for disease-modifying and prophylactic interventions. Enhanced sympathetic activity is a well-established contributor to the pathophysiology of hypertension, however the cellular and molecular changes that increase sympathetic neurotransmission are not known. The aim of this study was to identify key changes in the transcriptome in normotensive and spontaneously hypertensive rats. We validated 15 of our top-scoring genes using qRT-PCR, and network and enrichment analyses suggest that glutamatergic signalling plays a key role in modulating Ca2+ balance within these ganglia. Additionally, phosphodiesterase activity was found to be altered in stellates obtained from the hypertensive rat, suggesting that impaired cyclic nucleotide signalling may contribute to disturbed Ca2+ homeostasis and sympathetic hyperactivity in hypertension. We have also confirmed the presence of these transcripts in human donor stellate samples, suggesting that key genes coupled to neurotransmission are conserved. The data described here may provide novel targets for future interventions aimed at treating sympathetic hyperactivity associated with cardiovascular disease and other dysautonomias.

Neurotransmitter Switching Coupled to ß-Adrenergic Signaling in Sympathetic Neurons in Prehypertensive States.

Single or combinatorial administration of ß-blockers is a mainstay treatment strategy for conditions caused by sympathetic overactivity. Conventional wisdom suggests that the main beneficial effect of ß-blockers includes resensitization and restoration of ß1-adrenergic signaling pathways in the myocardium, improvements in cardiomyocyte contractility, and reversal of ventricular sensitization. However, emerging evidence indicates that another beneficial effect of ß-blockers in disease may reside in sympathetic neurons. We investigated whether ß-adrenoceptors are present on postganglionic sympathetic neurons and facilitate neurotransmission in a feed-forward manner. Using a combination of immunocytochemistry, RNA sequencing, Förster resonance energy transfer, and intracellular Ca2+ imaging, we demonstrate the presence of ß-adrenoceptors on presynaptic sympathetic neurons in both human and rat stellate ganglia. In diseased neurons from the prehypertensive rat, there was enhanced ß-adrenoceptor-mediated signaling predominantly via ß2-adrenoceptor activation. Moreover, in human and rat neurons, we identified the presence of the epinephrine-synthesizing enzyme PNMT (phenylethanolamine-N-methyltransferase). Using high-pressure liquid chromatography with electrochemical detection, we measured greater epinephrine content and evoked release from the prehypertensive rat cardiac-stellate ganglia. We conclude that neurotransmitter switching resulting in enhanced epinephrine release, may provide presynaptic positive feedback on ß-adrenoceptors to promote further release, that leads to greater postsynaptic excitability in disease, before increases in arterial blood pressure. Targeting neuronal ß-adrenoceptor downstream signaling could provide therapeutic opportunity to minimize end-organ damage caused by sympathetic overactivity.

Types of sleep problems in adults living with HIV/AIDS.

OBJECTIVE: To characterize specific types of sleep problems experienced by adults with HIV. METHOD: The design was cross-sectional involving sleep questionnaires, diaries, and wrist actigraphy. The convenience sample included 290 adults living with HIV, 22-77 years of age. Measures included self-report for sleep onset latency, and wrist actigraphy estimates of total sleep time at night, wake after sleep onset, and daytime sleep. RESULTS: Nearly half (45%) of the sample slept < 6 h per night. Difficulty falling asleep was reported by 34%, and 56% had fragmented sleep according to actigraphy; 20% had both problems, and 30% were good sleepers. Participants reporting difficulty falling asleep had actigraphy and clinical measures similar to the good sleepers, but subjectively they experienced greater sleep disturbance and symptom burden (particularly anxiety and morning fatigue) and reported more use of sleep medication. Participants with fragmented sleep reported low levels of sleep disturbance and symptom burden similar to the good sleepers, despite actigraphy measures indicating they obtained less sleep both at night and during the day. Sleep fragmentation was also associated with sociodemographic factors and slightly lower CD4+ T-cell counts. Participants reporting both sleep problems had actigraphy and clinical profiles similar to those who had only fragmented sleep, but their symptom experience was similar to participants with only sleep initiation difficulties. CONCLUSIONS: Findings support the need for targeting efforts to improve sleep for the majority of adults living with HIV/AIDS and tailoring interventions to the specific type of sleep problem regardless of the person's clinical and demographic profile.

Self-reported medication adherence and symptom experience in adults with HIV.

Symptom burden has been identified as a predictor of medication adherence, but little is known about which symptoms are most strongly implicated. This study examines self-reported medical adherence in relation to demographic, clinical, and symptom characteristics among 302 adults living with HIV. Only 12% reported missing medication during the 3-day assessment, but 75% gave at least one reason for missing it in the previous month. Poor adherence was associated with higher viral load and greater symptom burden. Trouble sleeping and difficulty concentrating were strongly associated with poor adherence. Given that "forgetting" was the most common reason for missing medication and nearly one third reported sleeping through dose time, future research should examine the influence of sleep disturbance on adherence. Effective management of common symptoms, such as sleep disturbance, fatigue, and gastrointestinal side-effects of medications may result in better adherence, as well as improved clinical outcomes and quality of life.

Predicting NCLEX-RN success in a diverse student population.

Many schools of nursing have implemented standardized testing using platforms such as those developed by Assessment Technologies Institute (ATI) to better prepare students for success on the National Council Licensure Examination for Registered Nurses® (NCLEX-RN). This study extends and replicates the research on standardized testing to predict first-time pass success in a diverse student population and across two prelicensure program types. The final sample consisted of 589 students who graduated between 2003 and 2009. Demographic data, as well as academic performance and scores on the ATI RN Comprehensive Predictor, were analyzed. The findings in this study indicate that scores on the ATI RN Comprehensive Predictor were positively, significantly associated with first-time pass success. Students in jeopardy of failing the NCLEX-RN on their first attempt can be identified prior to graduation and remediation efforts can be strengthened to improve their success.

Predictors of NCLEX-RN success across 3 prelicensure program types.

Nursing faculty are concerned about the ability of recent graduates to successfully pass NCLEX-RN on their first-attempt. To facilitate student first-time success on the examination, nurse educators need to understand what student characteristics are predictive of success. The purpose of this study was to explore student characteristics across 3 different programs types (university-based BSN, master's entry, and satellite BSN) and in each of the 3 program types to identify predicators of first-time NCLEX-RN success.

The social determinants of substance abuse in African American baby boomers: effects of family, media images, and environment.

Grounded theory methodology was used to explore the social processes involved in the use of illicit drugs in older African Americans as an underpinning to the development of approaches to nursing care and treatment. Interviews were conducted with six older African American substance users who were currently in drug treatment programs. Responses to the questions were recorded, transcribed, and analyzed using constant comparative methods. Three core themes emerged: (a) family, (b) media images, and (c) environment. The core issues of substance abuse, such as the environment and larger societal forces, cannot be addressed by one discipline and mandate that clinicians move to an interdisciplinary approach to achieve a plan of care for this growing population.

Metabolic abnormalities and coronary heart disease risk in human immunodeficiency virus-infected adults.

BACKGROUND: Metabolic syndrome is a combination of risk factors for cardiovascular disease and diabetes, It has been reported to be increased in human immunodeficiency virus (HIV)-infected individuals. METHODS: In a cohort of HIV-infected adults we examined parameters that contribute to defining the metabolic syndrome and to estimating the 10-year risk of coronary heart disease (CHD). The study group consisted of 296 participants (217 men and 79 women) of mixed ethnicity with a mean age of 45.3 years. RESULTS: There was an appreciable prevalence of metabolic syndrome (30.0%), with the frequency increasing to 42.5% in those over 50 years of age. Those with the metabolic syndrome had a lower viral load. More women had abdominal obesity (59.5%) than men (20.7%, P < 0.001). The frequency of elevated plasma glucose was higher in females (37.2%) compared to males (16.9%, P = 0.004). High frequencies of decreased high-density lipoprotein cholesterol (HDL-C) and elevated blood pressure were seen in both sexes. Hypertriglyceridemia was less prevalent in African Americans. In those under 50 years of age, the 10-year CHD risk score for men was double that for women (6.2% vs 2.7%, P < 0.001). In older participants, the risk was similar between the sexes, with a third having scores over 10%. CONCLUSIONS: The prevalence of metabolic syndrome was higher than in most other HIV cohorts. Those with the syndrome had significantly lower viral loads. Mean 10-year Framingham Cardiovascular Risk (FCR) scores were nearly doubled for those with metabolic syndrome. Both researchers and clinicians should consider age as well as sex when assessing patients with HIV infection for risks associated with metabolic syndrome.

Risk factors and symptoms associated with pain in HIV-infected adults.

Studies suggest that people living with HIV (PLWH) experience many unrelieved symptoms. The purpose of this study was to estimate the occurrence of pain in adult PLWH and to determine whether participants with pain differed from those without pain on selected demographic factors, clinical characteristics, symptoms of fatigue, sleep disturbance, anxiety, or depression. The authors conducted a descriptive, comparative, and correlational study of 317 PLWH seen at academic and community clinics in San Francisco. Participants completed a demographic questionnaire, the Memorial Symptom Assessment Scale, the Fatigue Severity Scale, the General Sleep Disturbance Scale, the Profile of Moods State Tension-Anxiety subscale, and the Center for Epidemiological Studies-Depression Scale. Clinical characteristics (i.e., disease and treatment information) were obtained by self-report. A single item on pain from the Memorial Symptom Assessment Scale was used to classify participants into those with and without pain. Pain was highly prevalent (55%) and was associated with immune status (CD4+ T-cell count), race, and sleep disturbance, but not with age, gender, or symptoms of fatigue, depression, or anxiety.

Symptom experience in HIV-infected adults: a function of demographic and clinical characteristics.

Personal characteristics that interact with both HIV diagnosis and its medical management can influence symptom experience. Little is known about how symptoms in populations with chronic illness vary by age, sex, or socioeconomic factors. As part of an ongoing prospective longitudinal study, this report describes symptoms experienced by 317 men and women living with HIV/AIDS. Participants were recruited at HIV clinics and community sites in the San Francisco Bay Area. Measures included the most recent CD4 cell count and viral load from the medical record, demographic and treatment variables, and the 32-item Memorial Symptom Assessment Scale to estimate prevalence, severity, and distress of each symptom and global symptom burden. The median number of symptoms was nine, and symptoms experienced by more than half the sample population included lack of energy (65%), drowsiness (57%), difficulty sleeping (56%), and pain (55%). Global symptom burden was unrelated to age or CD4 cell count. Those with an AIDS diagnosis had significantly higher symptom burden scores, as did those currently receiving antiretroviral therapy. African Americans reported fewer symptoms than Caucasians or Mixed/Other race, and women reported more symptom burden after controlling for AIDS diagnosis and race. Because high symptom burden is more likely to precipitate self-care strategies that may potentially be ineffective, strategies for symptom management would be better guided by tailored interventions from health care providers.