Examination of the autonomic nervous system at the bedside

Autonomic function is an integral part of the assessment of neurological disorders. However, pragmatically, it is often the most neglected part of neurological examination and is often limited to testing for orthostatic hypotension. Testing the autonomic nervous system may aid in the early diagnosis of neurodegenerative disorders, thereby enabling the initiation of neuroprotective strategies and resulting in improved quality of life in this group of patients. It may also enable differentiation between certain atypical parkinsonisms, such as Multiple System Atrophy and Dementia with Lewy Bodies, in which autonomic dysfunction is early and usually profound compared to Parkinson's disease. Our review focusses on the "first-line" autonomic function tests which can be done at the bedside and require use of minimal equipment and provide insights into cardiovascular, pupillary and sudomotor function. The use of minimal equipment underscores the value of these tests in resource-constrained settings as a major unmet need, thereby saving resources and avoiding delays in diagnosis and treatment.

Blood Pressure Patterns and Hepatosteatosis: Cardiometabolic Risk Assessment in Dipper and Non-Dipper Phenotypes

Background/Objectives: Non-dipper hypertension (HT), a condition in which blood pressure does not drop sufficiently at night compared to daytime, is considered a serious condition that increases the risk of cardiovascular disease, stroke, and organ damage. This study aimed to examine the relationship between dipper and non-dipper blood pressure patterns, hepatosteatosis, and biochemical markers in hypertensive and normotensive individuals. Methods: Demographic, biochemical, and hepatic ultrasonography data from 142 patients who underwent 24 h ambulatory blood pressure measurement (ABPM) were evaluated retrospectively and cross-sectionally in this study. Patients were categorized into four groups based on ABPM results: non-dipper normotensive (NDN), dipper normotensive (DN), non-dipper hypertensive (NDH), and dipper hypertensive (DH). Results: The study results indicate that NDH individuals had markedly elevated levels of hepatosteatosis and uric acid compared with DH and normotensive persons (p < 0.001). The grade of hepatosteatosis showed significant discriminatory capacity in differentiating between dipper and non-dipper hypertensive patients, with an AUC of 0.861, specificity of 94%, and sensitivity of 66%. Individuals with hypertension exhibiting a non-dipper pattern demonstrate a greater prevalence of hepatosteatosis and elevated uric acid levels. Conclusions: The study findings show non-dipper patterns have a higher risk for cardiometabolic diseases. This indicates that not only blood pressure, but also metabolic disorders should be closely monitored and treated in the management of non-dipper HT.

Diurnal variation of serum phosphorus concentrations in intact male adult domestic cats

BACKGROUND

Monitoring serum phosphorus concentrations is crucial in the management of chronic kidney disease in cats. The diurnal variation of serum phosphorus concentration may affect clinical assessment.

HYPOTHESIS/OBJECTIVES

Characterize the diurnal variation of serum phosphorus concentration in cats and determine the associations between changes in serum phosphorus concentration and several metabolites of phosphorus metabolism.

ANIMALS

Six apparently healthy, intact male, specific-pathogen-free cats were housed in a photoperiod, humidity, and temperature-controlled facility.

METHODS

Blood sampling was performed hourly for 24 hours to obtain the serum concentrations of phosphorus, ionized calcium, parathyroid hormone, and calcidiol. Results were analyzed using linear mixed-effect models to determine the significance of diurnal variation and associations between serum phosphorus concentrations and other metabolites over time.

RESULTS

Diurnal variation in serum phosphorus concentration was noted with an apex around 11:00 followed by gradually declining concentrations to reach the nadir around 23:00. The serum phosphorus concentration again increased through the early morning on the next day. An approximately 25% difference in serum phosphorus concentration at the apex and the nadir was documented. A non-linear relationship between the serum concentrations of phosphorus and ionized calcium over time was identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Diurnal variations of serum phosphorus concentration and associations between the trending of serum phosphorus and ionized calcium concentrations were evident in a group of clinically healthy adult cats housed in a controlled environment. These findings can help in the interpretation of clinical and research data regarding calcium and phosphorus metabolism and kidney health in cats.

Timing Is Important-Management of Metabolic Syndrome According to the Circadian Rhythm

Physiological processes occur in accordance with a rhythm regulated by the endogenous biological clock. This clock is programmed at the molecular level and synchronized with the daily light-dark cycle, as well as activities such as feeding, exercise, and social interactions. It consists of the core clock genes, Circadian Locomotor Output Cycles Protein Kaput (CLOCK) and Brain and Muscle Arnt-Like protein 1 (BMAL1), and their products, the period (PER) and cryptochrome (CRY) proteins, as well as an interlocked feedback loop which includes reverse-strand avian erythroblastic leukemia (ERBA) oncogene receptors (REV-ERBs) and retinoic acid-related orphan receptors (RORs). These genes are involved in the regulation of metabolic pathways and hormone release. Therefore, circadian rhythm disruption leads to development of metabolic syndrome (MetS). MetS refers to a cluster of risk factors (RFs), which are not only associated with the development of cardiovascular (CV) disease (CVD), but also with increased all-cause mortality. In this review, we consider the importance of the circadian rhythm in the regulation of metabolic processes, the significance of circadian misalignment in the pathogenesis of MetS, and the management of MetS in relation to the cellular molecular clock.

Divergent roles of angiotensin II upon the immediate and sustained increases of renal blood flow following unilateral nephrectomy

Although the molecular and functional responses related to renal compensatory hypertrophy after unilateral nephrectomy (UNX) has been well described, many aspects of these events remain unclear. One question is how the remaining kidney senses the absence of the contralateral organ, and another is what the role of the renin-angiotensin system is in these responses. Both acute anesthetized and chronic unanesthetized experiments were performed using the angiotensin II type 1 receptor blocker losartan and the renin inhibitor aliskiren to determine the contribution of the renin-angiotensin system to immediate changes and losartan for chronic changes of renal blood flow (RBF) and the associated hypertrophic events in male Sprague-Dawley rats. Chronic experiments used implanted RBF probes and arterial catheters for continuous data collection, and the glomerular filtration rate was determined by noninvasive transcutaneous FITC-sinistrin measurements. The results of the acute experiments found that RBF increased nearly 25% (4.6 ± 0.5 to 5.6 ± 0.6 mL/min/g kidney wt) during the first 15 min following UNX and that this response was abolished by losartan (6.7 ± 0.7 to 7.0 ± 0.7 mL/min/g kidney wt) or aliskiren (5.8 ± 0.4 to 6.0 ± 0.4 mL/min/g kidney wt) treatment. Thereafter, RBF increased progressively over 7 days, and kidney weight increased by 19% of pre-UNX values. When normalized to kidney weight determined at day 7 after UNX, RBF was not significantly different from pre-UNX levels. Semiquantification of CD31-positive capillaries revealed increases of the glomeruli and peritubular capillaries that paralleled the kidney hypertrophy. None of these chronic changes was inhibited by losartan treatment, indicating that neither the compensatory structural nor the RBF changes were angiotensin II type 1 receptor dependent.NEW & NOTEWORTHY This study found that the immediate increases of renal blood flow (RBF) following unilateral nephrectomy (UNX) are a consequence of reduced angiotensin II type 1 (AT1) receptor stimulation. The continuous monitoring of RBF and intermittent measurement of glomerular filtration rate (GFR) in conscious rats during the 1-wk period of rapid hypertrophy following UNX provided unique insights into the regulation of RBF and GFR when faced with increased metabolic loads. It was found that neither kidney hypertrophy nor the associated increase of capillaries was an AT1-dependent phenomenon.

Clocks, Rhythms, Sex, and Hearts: How Disrupted Circadian Rhythms, Time-of-Day, and Sex Influence Cardiovascular Health

Cardiovascular diseases are the top cause of mortality in the United States, and ischemic heart disease accounts for 16% of all deaths around the world. Modifiable risk factors such as diet and exercise have often been primary targets in addressing these conditions. However, mounting evidence suggests that environmental factors that disrupt physiological rhythms might contribute to the development of these diseases, as well as contribute to increasing other risk factors that are typically associated with cardiovascular disease. Exposure to light at night, transmeridian travel, and social jetlag disrupt endogenous circadian rhythms, which, in turn, alter carefully orchestrated bodily functioning, and elevate the risk of disease and injury. Research into how disrupted circadian rhythms affect physiology and behavior has begun to reveal the intricacies of how seemingly innocuous environmental and social factors have dramatic consequences on mammalian physiology and behavior. Despite the new focus on the importance of circadian rhythms, and how disrupted circadian rhythms contribute to cardiovascular diseases, many questions in this field remain unanswered. Further, neither time-of-day nor sex as a biological variable have been consistently and thoroughly taken into account in previous studies of circadian rhythm disruption and cardiovascular disease. In this review, we will first discuss biological rhythms and the master temporal regulator that controls these rhythms, focusing on the cardiovascular system, its rhythms, and the pathology associated with its disruption, while emphasizing the importance of the time-of-day as a variable that directly affects outcomes in controlled studies, and how temporal data will inform clinical practice and influence personalized medicine. Finally, we will discuss evidence supporting the existence of sex differences in cardiovascular function and outcomes following an injury, and highlight the need for consistent inclusion of both sexes in studies that aim to understand cardiovascular function and improve cardiovascular health.