Many diseases may reflect dysfunctions of autonomic balance attributable to evolutionary displacement

Neurodining: Common dietary factors may be substrates in novel biosynthetic pathways for monoaminergic neurotransmitters

It is not established that there are multiple endogenous mechanisms for synthesizing each of the three major monoamine neurotransmitters: serotonin, norepinephrine, and dopamine. Having multiple biosynthetic pathways for each of these important signaling molecules would provide greater assurance that they are available in sufficient quantities for their various physiological roles in the body. This paper puts forth the hypothesis that a number of common dietary factors-including sucrose and glucose, fats, plant components, and even ethanol-are substrates in novel biosynthetic pathways for the monoamines. A major aspect of this hypothesis is that in a range of multicellular organisms, D-glucose in particular may participate in novel biosynthetic pathways for the monoamines, where this sugar has already been linked with synthesis of the neurotransmitters acetylcholine, glutamate, and GABA through the tricarboxylic acid cycle. Another major aspect of the hypothesis is that phenol or polyphenol molecules, found in various plants, may combine with particular fats or even ethanol to form dopamine, which can then be converted to norepinephrine through the already established step involving the enzyme dopamine beta-hydroxylase. If such a biosynthetic pathway exists for converting ethanol to dopamine in humans, it could be a major factor in substance abuse, including early onset alcoholism. Further, if the above biosynthetic pathways exist in a range of organisms, they may be associated with appetitive processes regulating consumption of particular dietary factors, such as fruits and vegetables, to maintain internal "set points" of, for example, elevated noradrenergic signaling. In this scenario, exposure to psychological stress, which could eventually deplete neurotransmitters such as norepinephrine, may result in craving for sucrose, fats, or alcohol to help replenish the depleted cellular levels of this signaling molecule. An alternative to the overall biosynthetic hypothesis put forth here is that animal cells do not possess these pathways, but the animal microbiome harbors bacteria that do carry out these reactions and helps supply the body with monoamines and other signaling molecules.

A Copernican Approach to Brain Advancement: The Paradigm of Allostatic Orchestration

There are two main paradigms for brain-related science, with different implications for brain-focused intervention or advancement. The paradigm of homeostasis (“stability through constancy,” Walter Cannon), originating from laboratory-based experimental physiology pioneered by Claude Bernard, shows that living systems tend to maintain system functionality in the direction of constancy (or similitude). The aim of physiology is to elucidate the factors that maintain homeostasis, and therapeutics aim to correct abnormal factor functions. The homeostasis paradigm does not formally recognize influences outside its controlled experimental frames and it is variable in its modeling of neural contributions. The paradigm of allostatic orchestration (PAO) extends the principle of allostasis (“stability through change”) as originally put forth by Peter Sterling. The PAO originates from an evolutionary perspective and recognizes that biological set points change in anticipation of changing environments. The brain is the organ of central command, orchestrating cross-system operations to support optimal behavior at the level of the whole organism. Alternative views of blood pressure regulation and posttraumatic stress disorder (PTSD) illustrate differences between the paradigms. For the PAO, complexities of top-down neural effects and environmental context are foundational (not to be “factored out”), and anticipatory regulation is the principle of their interface. The allostatic state represents the integrated totality of brain-body interactions. Health itself is an allostatic state of optimal anticipatory oscillation, hypothesized to relate to the state of criticality, a mathematical point of poise between phases, on the border between order and disorder (or the “edge of chaos”). Diseases are allostatic states of impaired anticipatory oscillations, demonstrated as rigidifications of set points across the brain and body (disease comorbidity). Conciliation of the paradigms is possible, with “reactive homeostasis” resolved as an illusion stemming from the anticipation of environmental monotony. Considerations are presented with respect to implications of the two paradigms for brain-focused intervention or advancement; the hypothesis that the state of criticality is a vehicle for evolutionary processes; concordance with a philosophy of freedom based on ethical individualism as well as self-creativity, non-obsolescence, empowerment, and citizenship; and concluding reflections on the science and ethics of the placebo, and the potential for virtuous cycles of brain-Anthropocene interactions.

Rightward dominance in temporal high-frequency electrical asymmetry corresponds to higher resting heart rate and lower baroreflex sensitivity in a heterogeneous population

OBJECTIVE

Explore potential use of a temporal lobe electrical asymmetry score to discriminate between sympathetic and parasympathetic tendencies in autonomic cardiovascular regulation.

METHODS

131 individuals (82 women, mean age 43.1, range 13-83) with diverse clinical conditions completed inventories for depressive (CES-D or BDI-II) and insomnia-related (ISI) symptomatology, and underwent five-minute recordings of heart rate and blood pressure, allowing calculation of heart rate variability and baroreflex sensitivity (BRS), followed by one-minute, two-channel, eyes-closed scalp recordings of brain electrical activity. A temporal lobe high-frequency (23-36 Hz) electrical asymmetry score was calculated for each subject by subtracting the average amplitude in the left temporal region from amplitude in the right temporal region, and dividing by the lesser of the two.

RESULTS

Depressive and insomnia-related symptomatology exceeding clinical threshold levels were reported by 48% and 50% of subjects, respectively. Using a cutoff value of 5% or greater to define temporal high-frequency asymmetry, subjects with leftward compared to rightward asymmetry were more likely to report use of a sedative-hypnotic medication (42% vs. 22%, P = 0.02). Among subjects with asymmetry of 5% or greater to 30% or greater, those with rightward compared to leftward temporal high-frequency asymmetry had higher resting heart rate (≥5% asymmetry, 72.3 vs. 63.8, P = 0.004; ≥10%, 71.5 vs. 63.0, P = 0.01; ≥20%, 72.2 vs. 64.2, P = 0.05; ≥30%, 71.4 vs. 64.6, P = 0.05). Subjects with larger degrees of rightward compared to leftward temporal high-frequency asymmetry had lower baroreflex sensitivity (≥40% asymmetry, 10.6 vs. 16.4, P = 0.03; ≥50% asymmetry, 10.4 vs. 16.7, P = 0.05).

CONCLUSION

In a heterogeneous population, individuals with rightward compared to leftward temporal high-frequency electrical asymmetry had higher resting heart rate and lower BRS. Two-channel recording of brain electrical activity from bilateral temporal regions appears to hold promise for further investigation as a means to assess cortical activity associated with autonomic cardiovascular regulation.

Acupuncture Prevents Relapses of Recurrent Otitis in Dogs: A 1-Year Follow-Up of a Randomised Controlled Trial

Background

Recurrent infections within a particular, well-localised body location are often seen in veterinary and medical practice. This condition could represent a localised or segmental immune deficiency. Recurrent canine otitis seems to be one example of this problem. It has been reported that acupuncture increased the efficacy of conventional treatment for canine otitis by >50%.

Objective

To assess whether the relapse rate of recurrent canine otitis over 1 year can be modified by acupuncture in adult dogs.

Methods

One-year follow-up of a randomised controlled trial. 31 dogs with a history of recurring otitis were randomised into two groups. In addition to conventional treatment, each group received four sessions of either real acupuncture, group A (n=16), or sham acupuncture, group B (n=15). The main outcome for the follow-up was the rate of acute otitis episodes in each group over 1 year, with blinded evaluation. A χ2 test was used for statistical analysis.

Results

There was one dropout in each group. Fourteen (93%) dogs in group A: were free of otitis relapses, compared with 7 (50%) in group B (p<0.01).

Conclusion

Acupuncture seems effective for preventing relapses in cases of recurrent canine otitis. This result suggests that acupuncture could be tested as a treatment of other recurrent localised infections. Given the ability of acupuncture to modulate neurotransmitters and opioid peptides, which can in turn modulate the immune system, the immune response to acupuncture also seems worth exploring.

The hegemony of empiricism: The opportunity for theoretical science in medicine

Partly spurred by the rapid emergence of discovery tools, empirical science founded on experimental validation now dominates academic funding, publishing, and recognition while forums for theoretical science have been marginalized. Although this hegemony of empiricism instills useful discipline to the scientific process, it also limits the pace of science to sensor innovation and renders the ontogeny of scientific knowledge path-dependent, concealing potential discontinuities in intellectual trajectories. Theoretical science, founded on intuition, inspiration, and abstraction, can complement empirical science by creating disruptive paradigms that facilitate detection of spurious results and frame new hypotheses. For example, framing the compendium of human diseases as varying manifestations of buffer dysfunctions - insufficient or maladaptive responses to stress - portends new insights into disease mechanisms and treatments. As a specific incarnation of this theory, the "trauma hypothesis" suggests that the coordinated regulation of inflammation, coagulation, vasoconstriction, and fluid retention that evolved as a prehistoric adaptation to predatory stress and environmental injury conspires in modern times to produce acute coronary syndromes, heart failure, renal dysfunction, stroke, and pulmonary embolism. The theory also exposes the paradigmatic flaw behind the half-century detour perfecting balloon-deployed endovascular interventions. As the basis of buffer acquisition shifts from genetic to cognitive, phenoptosis - the theory that adaptive programmed death of organisms yields opportunity to successors - is rendered maladaptive, as an extended lifespan permits more efficient trait acquisition compared with life-death recycling. While forestalling death is a largely unfruitful medical game of "whack-a-mole" today, the recognition that aging and death may be programmed adaptations suggests they may also be amenable to systemic reprogramming. Epitomizing this opportunity are tumor cells, which reprogram themselves to escape their apoptotic fate and assume indefinite persistence. The prevalence and resilience of these cancer cells, and their ability to withstand the protean assaults of toxins, poisons, radiation, and host defenses, presage the potential robustness of life when appropriately programmed. Paradoxical medicine and dynamic range management may represent initial strategies to reprogram the neuroendocrine stress axes to modulate lifespan at the organism level, and many other strategies are anticipated. The key to theoretical science is original insight, but the prevailing pressure to conform to medicine's educational and practice standards dis-incentivizes independent thinking. A scientific future is envisioned when the commoditization of experimental science will enable its outsourcing, liberating health scientists from the tyranny of empiricism to engage in a more balanced process of discovery infused with theoretical considerations.

Stress dysfunctions as a unifying paradigm for illness: repairing relationships instead of individuals as a new gateway for medicine

Stress has been implicated as a risk factor for most diseases, but a mechanistic explanation behind such associations remains elusive. As emergent responses to stress, adaptations range from acute responses where extant system capabilities mitigate current stress, to longer-term responses where system plasticity buffers against future stress. The long compendium of human ailments manifests through a much shorter set of symptoms that may operate through the stress axis. We propose a unifying ontology for human illnesses that classifies stress dysfunctions according to types of Darwinian dysfunction - inadequate response with adequate adaptation, inadequate adaptation, inappropriate adaptation, and epiphenomena of adaptation. Examples include cancer as a bystander effect of increased biologic plasticity in response to stress, and infectious illness as a manifestation of mutually escalating stress in an otherwise commensal relationship between hosts and microbes. We explore the contributing role of man-made stresses that have emerged as humans increasingly remodel their environment. Examples include biologic decompensation associated with reliance on technology to buffer stress, and behavioral stress caused by the dislocation of kin networks that promotes illegitimate signaling. Dysfunctional relationships engender stress not only among humans, but also among individual organs; heart failure, renal failure, and carotid stenosis may represent examples of such conditions. If stress dysfunction is the Occam's razor of human illnesses, and derangements in biologic relationships induce stress dysfunctions, then the study of relationships - an incarnation of systems biology - may represent a new gateway for medicine.

The link between carotid artery disease and ischemic stroke may be partially attributable to autonomic dysfunction and failure of cerebrovascular autoregulation triggered by Darwinian maladaptation of the carotid baroreceptors and chemoreceptors

Carotid artery stenosis is generally thought to induce stroke by either compromising cerebral perfusion or inciting embolic phenomena. Carotid baroreceptors and chemoreceptors are vital adaptations for cerebrovascular autoregulation that can behave mal-adaptively in the setting of modern diseases such as atherosclerosis. We hypothesize that acute cerebrovascular events may be partially attributable to autonomic dysfunction and cerebrovascular autoregulatory failure secondary to carotid sensor maladaptations. Specifically, we propose that atherosclerotic disease at the carotid bifurcation can interfere with baroreceptor and chemoreceptor function by buffering against accurate detection of physical and chemical parameters. Misperceptions of hypoxia and hypotension can trigger sympathetic bias and autonomic dysfunction which perturb cerebrovascular autoregulation and vasomotor tone, thereby compromising cerebral perfusion. The preferential association of strokes with morning arousal, stress, acute physical activity, winter months, illness, and older age may relate to this phenomenon. Sympathetic bias promotes inflammation and coagulation, a link likely forged during prehistoric evolution when trauma represented a more significant factor in natural selection. In the setting of carotid sensor dysfunction, the resulting inflammation and coagulation can promote acute cardiovascular events. The ensuing cerebral ischemia can induce further derangement of cerebrovascular autoregulation and upregulate adrenergia, inflammation, and coagulation in a feed-forward manner. Inflammation and coagulation can also exacerbate carotid sensor dysfunction by iteratively worsening atherosclerosis. Angioplasty, stenting, and endarterectomy may inadvertently cause acute and chronic carotid sensor dysfunction through manipulation, material interposition, and balloon-induced baroreceptor injury. Acute strokes during these procedures may result from carotid sensor dysfunction rather than embolization. Carotid body and sinus electro-modulation and non-balloon atherectomy represent new methods to prevent or treat cerebrovascular events. Pharmacologic modulation of autonomic balance, such as adrenergic blockade, long presumed contraindicated due to risk of cerebral hypoperfusion, may counter-intuitively offer benefit during acute strokes. Novel diagnostic paradigms may include functional analysis of carotid sensors as well as measurement of the anatomic thickness of calcified and non-calcified plaque near the carotid body. Carotid sensor dysfunction may be a source of systemic sympathetic bias and autonomic dysfunction observed during aging and, by association, many of the ailments associated with senescence. Modulation of carotid sensors may yield pervasive health benefits beyond those found by treating cerebrovascular disease.

Peripheral arterial disease: a manifestation of evolutionary dislocation and feed-forward dysfunction

Peripheral arterial disease in the legs represents a subset of atherosclerosis that manifests a particularly sinister profile. A predominance of sympathetic activity in the periphery favors the development of neurogenic atherosclerosis. Atherosclerosis may then produce flow derangements and decreased physical activity that serves to escalate sympathetic bias in a vicious cycle. Restoration of normal flow in peripheral arterial disease may not only produce local benefit due to improved perfusion, but also represent a gateway to correcting many systemic conditions that may at first glance appear unrelated but share a common etiology of autonomic dysfunction, such as gout, acute coronary syndromes, stroke, sleep apnea, arrhythmias, depression, erectile dysfunction, inflammation, hypercoagulability, sleep disorders, bowel dysfunction, renal failure, and aging.

Osteoarthritis: an example of phenoptosis through autonomic dysfunction?

Phenoptosis, the programmed death of organisms akin to cellular apoptosis, constitutes a type of Darwinian selection that enhances inclusive fitness. It provides a means by which senescent and pre-senescent members can self-terminate if they have incurred sufficient cumulative stress such that their continued survival detracts from inclusive fitness. Sepsis, vascular disease, menopause, cancer, and aging all represent examples of phenoptosis at work. We previously proposed that feed-forward autonomic dysfunction fundamentally drives phenoptosis in all its guises. Accordingly, we now postulate that osteoarthritis defines a type of biomechanical phenoptosis, mediated by feed-forward autonomic dysfunction, and manifested through joint destruction associated with fitness disadvantages. Biomechanical capability plays a significant role in evolutionary fitness, and sustained joint insults such as immobility or undue biomechanical stress may serve as proxies for inferior fitness. By both hindering an individual's ability to compete for energy and increasing that individual's vulnerability to predation, feed-forward joint destruction may facilitate adaptive phenoptosis among impaired or senile members. Empirical data suggests that contrary to common belief, heavy joint use does not necessarily cause osteoarthritis, whereas immobility and neuropathy can predispose to the condition. From a Darwinian perspective, another process mediated by sympathetic activity, the alarm cry of attacked prey, simultaneously promotes the escape of kin while attracting predators and scavengers. By effectively enabling the martyrdom of biomechanically-challenged individuals, osteoarthritis may serve to optimize system energy efficiency in a similar fashion. This framework may generalize to other situations where regenerative capacity dissipates in conjunction with maturation, typically leading to fibrosis. By allowing environmental pressure to sort the phenotypes, imperfect repair mechanisms may accelerate adaptation and optimize long-term inclusive fitness for all individuals. As the basis of competition shifts from biomechanical to cognitive skills, and as novel triggers for physical stress emerge, osteoarthritis may now represent a modern maladaptation.

A paradigm for viewing biologic systems as scale-free networks based on energy efficiency: Implications for present therapies and the future of evolution

A network constitutes an abstract description of the relationships among entities, respectively termed links and nodes. If a power law describes the probability distribution of the number of links per node, the network is said to be scale-free. Scale-free networks feature link clustering around certain hubs based on preferential attachments that emerge due either to merit or legacy. Biologic systems ranging from sub-atomic to ecosystems represent scale-free networks in which energy efficiency forms the basis of preferential attachments. This paradigm engenders a novel scale-free network theory of evolution based on energy efficiency. As environmental flux induces fitness dislocations and compels a new meritocracy, new merit-based hubs emerge, previously merit-based hubs become legacy hubs, and network recalibration occurs to achieve system optimization. To date, Darwinian evolution, characterized by innovation sampling, variation, and selection through filtered termination, has enabled biologic progress through optimization of energy efficiency. However, as humans remodel their environment, increasing the level of unanticipated fitness dislocations and inducing evolutionary stress, the tendency of networks to exhibit inertia and retain legacy hubs engender maladaptations. Many modern diseases may fundamentally derive from these evolutionary displacements. Death itself may constitute a programmed adaptation, terminating individuals who represent legacy hubs and recalibrating the network. As memes replace genes as the basis of innovation, death itself has become a legacy hub. Post-Darwinian evolution may favor indefinite persistence to optimize energy efficiency. We describe strategies to reprogram or decommission legacy hubs that participate in human disease and death.

A general theory of evolution based on energy efficiency: its implications for diseases

We propose a general theory of evolution based on energy efficiency. Life represents an emergent property of energy. The earth receives energy from cosmic sources such as the sun. Biologic life can be characterized by the conversion of available energy into complex systems. Direct energy converters such as photosynthetic microorganisms and plants transform light energy into high-energy phosphate bonds that fuel biochemical work. Indirect converters such as herbivores and carnivores predominantly feed off the food chain supplied by these direct converters. Improving energy efficiency confers competitive advantage in the contest among organisms for energy. We introduce a term, return on energy (ROE), as a measure of energy efficiency. We define ROE as a ratio of the amount of energy acquired by a system to the amount of energy consumed to generate that gain. Life-death cycling represents a tactic to sample the environment for innovations that allow increases in ROE to develop over generations rather than an individual lifespan. However, the variation-selection strategem of Darwinian evolution may define a particular tactic rather than an overarching biological paradigm. A theory of evolution based on competition for energy and driven by improvements in ROE both encompasses prior notions of evolution and portends post-Darwinian mechanisms. Such processes may involve the exchange of non-genetic traits that improve ROE, as exemplified by cognitive adaptations or memes. Under these circumstances, indefinite persistence may become favored over life-death cycling, as increases in ROE may then occur more efficiently within a single lifespan rather than over multiple generations. The key to this transition may involve novel methods to address the promotion of health and cognitive plasticity. We describe the implications of this theory for human diseases.

The smoking gun: many conditions associated with tobacco exposure may be attributable to paradoxical compensatory autonomic responses to nicotine

Tobacco exposure is implicated in many illnesses such as cardiovascular disease and cancer, but the mechanisms underlying these associations are poorly understood. The mechanisms by which tobacco induces pro-sympathetic and pro-inflammatory changes also remain elusive. Some studies have attributed these changes to the direct effects of nicotine, but such findings run counter to the pro-vagal, anti-inflammatory nature of the nicotinic pathway. We hypothesize that the illnesses associated with smoking may be partly attributable to autonomic dysfunction, sympathetic bias, and T helper (Th)2 inflammation induced by a paradoxical compensatory response to intermittent nicotinic exposure. The confusion of interpreting the adrenergia and inflammation associated with nicotine as a primary response instead of a secondary compensation may be explained by the unusually rapid absorption, action, and serum elimination of nicotine. Given the fast action and clearance of nicotine, even heavy smokers spend large portions of the day and the entire night in nicotine withdrawal, at which time rebound sympathetic bias may manifest as a result of desensitization of nicotinic receptors. This may help reconcile why the features observed in smokers such as tachycardia, hypertension, inflammation, insomnia, and anxiety, which are perhaps mistakenly attributed to the direct action of nicotine, are identical to those seen during acute nicotine withdrawal after smoking cessation. On the other hand, delayed responses to cessation of smoking such as weight gain and increased heart rate variability are compatible with reduced sympathovagal ratio and resensitization of nicotinic receptors. Sympathetic bias and the associated Th2 inflammation underlie many systemic diseases. Tobacco-related cancers may be partly attributable to immunomodulatory properties of chronic nicotine exposure by dampening Th1 immunity and enabling tumoral evasion of immune surveillance. Other conditions associated with tobacco exposure may also operate through similar autonomic and immune dysfunctions. Therapeutic implications are discussed.

Can thromboembolism be the result, rather than the inciting cause, of acute vascular events such as stroke, pulmonary embolism, mesenteric ischemia, and venous thrombosis?: a maladaptation of the prehistoric trauma response

Thromboembolism is considered the inciting cause of many vascular disorders including acute coronary syndrome (ACS), ischemic stroke, pulmonary embolism (PE), deep vein thrombosis (DVT), and mesenteric ischemia. Adrenergia and inflammation are known to accompany these conditions, particularly among arterial thromboembolic disorders, but the teleologic basis of these associations remains poorly understood. We argue that thromboembolism may sometimes be the result, rather than the cause, of acute vascular events, and may be precipitated by underlying adrenergia. Thromboembolic events are most prone to occur during parts of the circadian, seasonal, lifespan, and reproductive cycles with sympathetic dominance, as well as during behavioral, exertional, physiologic, and iatrogenic activation of sympathetic stress. Molecular evidence suggests that adrenergia and inflammation can promote coagulation and lead to co-activation of the pathways. Acute vascular events that occur without angiographic evidence of occlusion suggest that some infarcts may be attributable to adrenergia alone. "Embolic" disorders may represent asynchronous systemic phenomena rather than clot migration. During acute thromboembolism, downstream tissue hypoxia can activate maladaptive self-propelling cycles of sympathetic bias, inflammation, and coagulation. The counterproductive co-activation of these pathways may reflect a maladaptive interlink forged during the primordial evolution of trauma physiology. Their rapid co-mobilization enables rapid control of hemorrhage, microbial defense, and perfusion maintenance during trauma, but the pathways may behave maladaptively in the setting of modern diseases where endothelial injury may be more often precipitated by smoking, diabetes, dyslipidemia, or hypertension. Sympathetic blockade is already employed in ACS, and beta-blockers are used as antihypertensives to prevent stroke. Our hypothesis suggests that the benefits of beta-blockers in stroke may be independent of antihypertensive effects, and that adrenergia may represent a target for managing all thromboembolic disorders, independent of anti-coagulative and thrombolytic therapies. Perhaps reducing adrenergia, rather than maintaining high cerebral perfusion pressure, may represent a counterintuitive strategy for treating stroke and for reducing reperfusion injury. Plausible mechanisms by which autonomic dysfunction may induce venous thrombosis are discussed, especially in those with baroreceptor dysfunction, immobilization, or dehydration. Unexplained hypercoagulability of cancer may also operate through tumor-induced adrenergia and inflammation.

Clinical benefits of hydration and volume expansion in a wide range of illnesses may be attributable to reduction of sympatho-vagal ratio

Hydration and volume expansion regimens are widely thought to offer symptomatic benefit in many human ailments. Many varied theories for the phenomenon exists such as decreased blood viscocity in cardiac disease, dilution of toxins in cancer, and cleansing effect on airways in asthma. While it is plausible that disparate mechanisms are involved in different conditions, we propose an alternative, unifying hypothesis that many of the clinical benefits of hydration and volume expansion are partly related to reduced sympatho-vagal ratio. Hypovolemia triggers baroreceptor-mediated sympathetic response and neurohormonal activation to promote fluid retention. Emerging evidence suggests that many diseases including cardiovascular, neurologic, gastrointestinal, metabolic, inflammatory, thrombotic, viral, and oncologic conditions are manifestations of abnormal sympathetic bias and associated T helper 2 bias. Hypovolemia-induced sympathetic activation, especially if baroreceptor dysfunction is involved, can worsen these conditions. Hydration and volume expansion may lower sympatho-vagal ratio, thereby tempering a wide variety of clinical conditions linked directly or indirectly to adrenergia including, but not limited to, acute coronary syndromes, asthma, cancer, and stroke. Interestingly, isotonic or hypertonic hydration, rather than a low-salt diet, may be a counterintuitive potential strategy to treat some cases of hypertension associated with dehydration and autonomic dysfunction. In contrast to the putative causal relationship between them, perhaps hypertension and end-organ damage represent independent consequences of dysfunctional sympathetic and neurohormonal activation. Venipuncture enables faster volume expansion but may also be a source of sympathetic hyperactivity. Oral hydration may additionally promote vagal tone by triggering gastric distension, a benefit not offered by intravenous fluids. The empiric benefits of hydration and volume expansion portend novel methods to treat a wide range of clinical conditions through pharmacologic or electrical modulation of cardiovascular or gastrointestinal baroreceptors.

A new mechanism for diverticular diseases: aging-related vagal withdrawal

It is widely believed that diverticulosis, a common condition among the elderly, results from repeated colonic barotrauma related to low dietary fiber and low stool bulk. Recent evidence has challenged the dietary-barotrauma hypothesis. We propose an alternative hypothesis that diverticulosis may be attributable to colonic smooth muscle dysfunction that results from vagal attrition associated with aging. We previously proposed that broad aging-related attrition of autonomic nerves may unmask intrinsic sympathetic bias of end-organs, leading to the compendium of familiar conditions associated with senility. Unexplained cholinergic hypersensitivity and receptor over-expression in bowel affected by diverticulosis have recently been observed. These findings are highly suggestive of a compensatory response to loss of vagal innervation. The resulting autonomic dysregulation may induce bowel smooth muscle dysfunction, setting the stage for diverticula formation. Thus, diverticular bowel disease may be a manifestation of the aging-related systemic vagal withdrawal. The framework may extend to diverticula formation in other parts of the gastrointestinal and genitourinary tracts. For instance, aging-related vagal attrition may represent the common upstream mechanism that induces both sphincter of Oddi dysfunction and peri-ampullary duodenal diverticula, conditions that frequently occur together. Novel approaches to preventing and treating diverticular diseases by promoting vagal activity are proposed including the electrical or pharmacologic modulation of the autonomic system.

The dynamic range of biologic functions and variation of many environmental cues may be declining in the modern age: implications for diseases and therapeutics

We hypothesize that declining dynamic range and variation of environmental cues may contribute to health dysfunctions, and that judicious expansion of biologic dynamic ranges may be beneficial. Three disparate examples involving the endocrine, autonomic, and musculoskeletal systems are discussed. Daytime sheltering, optical shading, and nighttime use of artificial light may reduce circadian luminal variation. The resulting melatonin alterations may contribute to systemic dysfunctions. Loss of temporal variation of other hormones may contribute to biologic dysfunctions, especially those involving the hypothalamic-pituitary axis. Reduced variation of physical exertion, environmental stressors, and thermal gradients that characterize modern lifestyles may reduce the autonomic dynamic range resulting in lowered heart rate variability and a myriad of systemic dysfunctions. The health benefits of activities such as exercise, meditation, acupuncture, coitus, and laughter may operate through increasing autonomic variability. Reduced physical exertion also accounts for declining dynamic range of musculoskeletal function. The resulting muscle atrophy, fat infiltration, and sarcomere shortening may not only have deleterious local effects, but may also be involved in systemic metabolic dysfunctions such as insulin resistance. The extent to which our endogenous systems rely on environmental variation for self-tuning and the impact that under-utilization of compensatory mechanisms has on biologic function are not well understood. Modern therapeutic approaches generally result in reversion to the mean of physiologic functions and may buffer against variation. For example, beta-blockers are given to reduce adrenergic excess, insulin to treat insulin insufficiency, serotonin-reuptake inhibitors for depression, and refractive lenses for myopia. By undermining the demand for native compensatory functions, such therapeutic strategies may actually impair future ability to respond to biologic disequilibria. Generalizing from these observations, we anticipate benefits of therapeutic and lifestyle approaches that expand, rather than reduce, the dynamic range of many biologic experiences.

Paradoxical strategy for treating chronic diseases where the therapeutic effect is derived from compensatory response rather than drug effect

Reversing chronic conditions remains an elusive goal of medicine. The modern medical paradigm based on blocking overactive pathways or augmenting deficient pathways offers symptomatic benefit, but tolerance to therapy can develop and treatment cessation can produce rebound symptoms due to compensatory mechanisms. We propose a paradoxical strategy for treating chronic conditions based on harnessing compensatory mechanisms for therapeutic benefit. Many current drugs may be repurposed for a paradoxical indication where the therapeutic effect is derived from compensatory response, rather than drug effect. For example, although exercise is associated with acute adrenergia, paradoxical downregulation of baseline sympathovagal ratio occurs as a remodeling response. For conditions that manifest chronic sympathetic bias such as cardiovascular diseases, judicious administration of adrenergic agonists may induce compensatory downregulation of baseline sympathovagal ratio. The concept may generalize to many other diseases, especially those involving pathways which exhibit strong homeostatic tendencies such as the neurologic, immune, and endocrine systems. Careful consideration of chronobiologic features is necessary to optimize dosing strategies for modulating compensatory responses, and eccentric dosing schedules, shorter-acting formulations, or pulsatile delivery may be desirable in some cases. To what extent the effect of desensitization to current therapy is mistaken for disease progression in conditions such as diabetes, myopia, depression, and hypertension warrants investigation. The merits of combining behavioral and drug therapies such as diet-insulin therapy for diabetes and exercise-beta-blockade for cardiovascular disease should be revisited since there is a risk for exacerbating the underlying dysfunction. The reduced dynamic range of various environmental experiences and the tendency to revert to the mean through medical intervention, thermoregulation, and other modern lifestyle changes may play under-recognized roles in human diseases. Perhaps alternating agonists and antagonist may exercise the entire dynamic range of pathways and improve health.

Modulation of autonomic balance by tumors and viruses

Autonomic balance, a function generally under host control, is subject to modulation by other signalers. In some cases, modulation of host autonomic function through behavioral and physical stressors exerted by another individual may have negative consequences for the stress recipient by inducing sympathetic bias. Modulation of autonomic function may sometimes benefit one party at the expense of another. Tumors and HIV are examples of illegitimate signalers who may induce host sympathetic bias to promote their own growth and evade host immune surveillance. Paraneoplastic and paraviral syndromes such as hypertrophic osteoarthopathy, QTc prolongation, insomnia, and cachexia could be viewed as epiphenomena related to the tumoral and viral manipulation of host autonomic balance. In a more general framework, other paraneoplastic and paraviral syndromes may represent epiphenomena related to modulation of endocrine, cytokine, and autonomic functions by tumors and viruses to promote their own survival. Spatial distribution of cancers and viruses within the host may reflect affinity for strategic locations that facilitate manipulation of a variety of host functions including autonomic, endocrine, and cytokine regulation. A more general for understanding spatial distribution of diseases based on gradients of autonomic balance in the body are explored. Darwinian perspectives are discussed.