The altered homeostatic theory: A hypothesis proposed to be useful in understanding and preventing ischemic heart disease, hypertension, and diabetes – including reducing the risk of age and atherosclerosis

Sex differences in diabetes‑induced hepatic and renal damage

Diabetes mellitus (DM) is a disease that affects millions of individuals worldwide and is characterized by abnormal glucose metabolism that can induce severe damage to numerous organs throughout the body. Sex differences have been demonstrated in a number of factors associated with diabetes and its complications, such as diabetic kidney disease and diabetic liver disease. To investigate the sex differences in DM further, the changes in the weight, food and water intake, and blood sugar of mice were recorded for 8 weeks in the present study. Hematoxylin and eosin staining, Masson's trichrome staining and transmission electron microscopy were used to observe the pathological changes of liver and kidney tissues. There is no significant difference in the water intake and blood glucose concentration between db/db female and male mice was observed. However, sex differences in liver and kidney damage including glomerular injury and hepatic fibrosis were found. In conclusion, the present study characterized the features of liver and kidney damage in db/db mice and indicated that sex differences should be taken into account in experiments using female and male experimental animals. Furthermore, sex differences should be taken into account in the selection of drug interventions in experiments and in clinical drug therapy.

Long-Term Effects of Ivabradine on Cardiac Vagal Parasympathetic Function in Normal Rats

Background: The complex interactions that exist between the pacemaker current, I _f, and the parasympathetic nervous system could significantly influence the course of patients undergoing chronic therapy with the I _f blocker ivabradine. We thus aimed to assess the effects of chronic ivabradine therapy on autonomic modulation and on the cardiovascular response to in situ and in vitro parasympathetic stimulation. The right atrial expression of HCN genes, encoding proteins for I _f, was also evaluated. Methods: Sympathetic and parasympathetic heart rate variability parameters and right atrial HCN(1-4) RNA levels were analyzed in 6 Control and 10 ivabradine-treated male Wistar rats (IVA; 3 weeks, 10 mg/kg/day). The heart rate (HR) and systolic blood pressure (SBP) responses to in situ electrical stimulation of the vagus nerve (2-20 Hz) were assessed in 6 additional Control and 10 IVA rats. The spontaneous sinus node discharge rate (SNDR) response to in vitro cholinergic receptors stimulation using carbamylcholine (10^-9-10^-6 mol/L) was also assessed in these later rats. Results: Ivabradine significantly increased vagal modulation and shifted the sympatho-vagal balance toward vagal dominance. In Control, in situ vagus nerve stimulation induced progressive decrease in both the SBP (p = 0.0001) and the HR (p< 0.0001). Meanwhile, in IVA, vagal stimulation had no effect on the HR (p = 0.16) and induced a significantly lower drop in SBP (p< 0.05). IVA also displayed a significantly lower SNDR drop in response to carbamylcholine (p< 0.01) and significantly higher right atrial HCN4 expression (p = 0.02). Conclusion: Chronic ivabradine administration enhanced vagal modulation in healthy rats. In addition, ivabradine reduced the HR response to direct muscarinic receptors stimulation, canceled the cardioinhibitory response and blunted the hemodynamic response to in situ vagal stimulation. These data bring new insights into the mechanisms of ivabradine-related atrial proarrhythmia and suggest that long-term I _f blockade may protect against excessive bradycardia induced by acute vagal activation.

Familial history of hypertension-induced impairment on heart rate variability was not observed in strength-trained subjects

Family history of hypertension is an important predictive factor for hypertension and is associated with hemodynamic and autonomic abnormalities. Previous studies reported that strength training might reduce arterial blood pressure (AP), as well as improve heart rate variability (HRV). However, the benefits of strength training in the offspring of hypertensive parents have not been fully evaluated. Here, we analyzed the impact of strength training on hemodynamics and autonomic parameters in offspring of hypertensive subjects. We performed a cross-sectional study with sedentary or physically active offspring of normotensives (S-ON and A-ON) or hypertensives (S-OH and A-OH). We recorded RR interval for analysis of HRV. AP was similar between groups. Sedentary offspring of hypertensives presented impairment of total variance of RR interval, as well as an increase in cardiac sympathovagal balance (S-OH: 4.2±0.7 vs S-ON: 2.8±0.4 and A-ON: 2.4±0.1). In contrast, the strength-trained group with a family history of hypertension did not show such dysfunctions. In conclusion, sedentary offspring of hypertensives, despite displaying no changes in AP, showed reduced HRV, reinforcing the hypothesis that autonomic dysfunctions have been associated with higher risk of hypertension onset. Our findings demonstrated that strength-trained offspring of hypertensives did not present impaired HRV, thus reinforcing the benefits of an active lifestyle in the prevention of early dysfunctions associated with the onset of hypertension in predisposed populations.

Cardiac autonomic modulation induced by doxorubicin in a rodent model of colorectal cancer and the influence of fullerenol pretreatment

The very effective anticancer drug doxorubicin (DOX) is known to have cardiotoxic side effects, which could be accompanied by autonomic modulation. Autonomic disbalance might even be an initiating mechanism underlying DOX-induced cardiotoxicity and can be studied noninvasively by the analysis of heart rate variability (HRV). A number of strategies have been assessed to predict chemotherapy-induced cardiac dysfunction while HRV, a potential detecting tool, has not yet been tested. Thus, we aimed to determine the effect of DOX treatment on HRV in a rat model of colorectal cancer. While pretreatment with fullerenol (Frl) acts protectively on DOX-induced cardiotoxicity, we aimed to test the effect of Frl pretreatment on DOX-induced HRV alterations. After the induction of colorectal cancer, adult male Wistar rats were treated with saline (n = 7), DOX (1.5 mg/kg per week, n = 7) or DOX after pretreatment with Frl (25 mg/kg per week, n = 7) for three weeks (cumulative DOX dose 4.5 mg/kg). One week after treatment rats were anaesthetized, standard ECG was measured and HRV was analyzed in time and frequency domain. During autopsy the intestines and hearts were gathered for biochemical analysis and histopathological examination. DOX treatment significantly decreased parasympathetically mediated high-frequency component (p<0.05) and increased the low-frequency component of HRV (p<0.05), resulting in an increased LF/HF ratio (p<0.05) in cancerous rats. When pretreated with Frl, DOX-induced HRV alterations were prevented: the high-frequency component of HRV increased (p<0.01), the low-frequency decreased (p<0.01), LF/HF ratio decreased consequently (p<0.01) compared to DOX only treatment. In all DOX-treated animals, disbalance of oxidative status in heart tissue and early myocardial lesions were found and were significantly reduced in rats receiving Frl pretreatment. Autonomic modulation accompanied the development of DOX-induced cardiotoxicity in rat model of colorectal cancer and was prevented by Frl pretreatment. Our results demonstrated the positive prognostic power of HRV for the early detection of DOX-induced cardiotoxicity.

Blood pressure and cardiovascular morbidity risk in type 2 diabetes with hypertension over a decade of follow-up: evidence for J-shaped phenomenon

There is still debate on whether the relationship between blood pressure (BP) and risk of cardiovascular diseases (CVD) in patients with type 2 diabetes (T2D) is linear or not. Since these cardio-metabolic disturbances share interrelated complex pathogenic mechanisms, we aimed to assess the relationship of baseline systolic (SBP)/diastolic pressures with CVD and coronary heart disease (CHD) events in a cohort of Iranians with T2D during a median follow-up of 8.8 years. Of all 1009 eligible participants with T2D with a mean (s.d.) age of 54.4 (11.6) years and free of CVD at baseline, we primarily focused on 260 participants undergoing anti-hypertensive treatment. Multivariate Cox proportional hazard models were used to evaluate hazard ratios (HR) of BP categories for CVD and CHD events. Also, multivariable regression modelling was applied to obtain their risk curve. We detected a J-shaped phenomenon between the continuous baseline BP and risk of CVD events. Considering 130⩽SBP<140 mm Hg as reference, a SBP ⩾140 mm Hg was associated with increased CVD (HR [95% confidence interval (CI)]: 2.43 [1.23-4.82]) and CHD (HR [95% CI]: 2.05 [1.02-4.13]) risk. However, a SBP⩽120 mm Hg in those with drug-treated hypertension also showed higher risk for CVD (HR [95% CI]: 2.80 [1.24-6.34]) and CHD events (HR [95% CI]: 2.39 [1.03-5.57]). Our findings revealed that the risk for macrovascular morbidity events was inversely associated with BP reduction below the level of 120/80 mm Hg for those with diabetes. People with diabetes might benefit from a BP management to a moderate range of 120/80-140/90 mm Hg for CVD risk reduction.

Meditation as a therapeutic intervention for adults at risk for Alzheimer's disease - potential benefits and underlying mechanisms

Alzheimer's disease (AD) is a chronic, progressive, brain disorder that affects at least 5.3 million Americans at an estimated cost of $148 billion, figures that are expected to rise steeply in coming years. Despite decades of research, there is still no cure for AD, and effective therapies for preventing or slowing progression of cognitive decline in at-risk populations remain elusive. Although the etiology of AD remains uncertain, chronic stress, sleep deficits, and mood disturbance, conditions common in those with cognitive impairment, have been prospectively linked to the development and progression of both chronic illness and memory loss and are significant predictors of AD. Therapies such as meditation that specifically target these risk factors may thus hold promise for slowing and possibly preventing cognitive decline in those at risk. In this study, we briefly review the existing evidence regarding the potential utility of meditation as a therapeutic intervention for those with and at risk for AD, discuss possible mechanisms underlying the observed benefits of meditation, and outline directions for future research.

High-throughput identification of off-targets for the mechanistic study of severe adverse drug reactions induced by analgesics

Drugs may induce adverse drug reactions (ADRs) when they unexpectedly bind to proteins other than their therapeutic targets. Identification of these undesired protein binding partners, called off-targets, can facilitate toxicity assessment in the early stages of drug development. In this study, a computational framework was introduced for the exploration of idiosyncratic mechanisms underlying analgesic-induced severe adverse drug reactions (SADRs). The putative analgesic-target interactions were predicted by performing reverse docking of analgesics or their active metabolites against human/mammal protein structures in a high-throughput manner. Subsequently, bioinformatics analyses were undertaken to identify ADR-associated proteins (ADRAPs) and pathways. Using the pathways and ADRAPs that this analysis identified, the mechanisms of SADRs such as cardiac disorders were explored. For instance, 53 putative ADRAPs and 24 pathways were linked with cardiac disorders, of which 10 ADRAPs were confirmed by previous experiments. Moreover, it was inferred that pathways such as base excision repair, glycolysis/glyconeogenesis, ErbB signaling, calcium signaling, and phosphatidyl inositol signaling likely play pivotal roles in drug-induced cardiac disorders. In conclusion, our framework offers an opportunity to globally understand SADRs at the molecular level, which has been difficult to realize through experiments. It also provides some valuable clues for drug repurposing.

Thiazolidine-2,4-diones: progress towards multifarious applications

The promising activity shown by compounds containing thiazolidine-2,4-dione nucleus in numerous categories such as anti-hyperglycaemics, aldose reductase inhibitors, anti-cancer, anti-inflammatory, anti-arthritics, anti-microbials, etc. has made it an indispensable anchor for development of new therapeutic agents. Varied substituents on the thiazolidine-2,4-dione nucleus have provided a wide spectrum of biological activities. Importance of this nucleus in some activities like, peroxisome proliferator activated receptor γ (PPARγ) agonism and PPARγ-dependent and -independent anti-cancer activities are reviewed separately in literature. Short reviews on biological importance of this nucleus are also known in literature. However, owing to fast development of new drugs possessing thiazolidine-2,4-dione nucleus many research reports are generated in short span of time. So, there is a need to couple the latest information with the earlier information to understand the current status of thiazolidine-2,4-dione nucleus in medicinal chemistry research. In the present review, various derivatives of thiazolidine-2,4-diones with different pharmacological activities are described on the basis of substitution pattern around the nucleus combined with the docking studies performed in the active site of the corresponding receptors with an aim to help medicinal chemists for developing an SAR on thiazolidine-2,4-dione derived compounds for each activity. This discussion will further help in the development of novel thiazolidine-2,4-dione compounds.

Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents

OBJECTIVES

The aim of this study was to evaluate cardiovascular autonomic function in a rodent obesity model induced by monosodium glutamate injections during the first seven days of life.

METHOD

The animals were assigned to control (control, n = 10) and monosodium glutamate (monosodium glutamate, n = 13) groups. Thirty-three weeks after birth, arterial and venous catheters were implanted for arterial pressure measurements, drug administration, and blood sampling. Baroreflex sensitivity was evaluated according to the tachycardic and bradycardic responses induced by sodium nitroprusside and phenylephrine infusion, respectively. Sympathetic and vagal effects were determined by administering methylatropine and propranolol.

RESULTS

Body weight, Lee index, and epididymal white adipose tissue values were higher in the monosodium glutamate group in comparison to the control group. The monosodium glutamate-treated rats displayed insulin resistance, as shown by a reduced glucose/insulin index (-62.5%), an increased area under the curve of total insulin secretion during glucose overload (39.3%), and basal hyperinsulinemia. The mean arterial pressure values were higher in the monosodium glutamate rats, whereas heart rate variability (>7 times), bradycardic responses (>4 times), and vagal (~38%) and sympathetic effects (~36%) were reduced as compared to the control group.

CONCLUSION

Our results suggest that obesity induced by neonatal monosodium glutamate treatment impairs cardiac autonomic function and most likely contributes to increased arterial pressure and insulin resistance.

Sympathetic overactivity precedes metabolic dysfunction in a fructose model of glucose intolerance in mice

Consumption of high levels of fructose in humans and animals leads to metabolic and cardiovascular dysfunction. There are questions as to the role of the autonomic changes in the time course of fructose-induced dysfunction. C57/BL male mice were given tap water or fructose water (100 g/l) to drink for up to 2 mo. Groups were control (C), 15-day fructose (F15), and 60-day fructose (F60). Light-dark patterns of arterial pressure (AP) and heart rate (HR), and their respective variabilities were measured. Plasma glucose, lipids, insulin, leptin, resistin, adiponectin, and glucose tolerance were quantified. Fructose increased systolic AP (SAP) at 15 and 60 days during both light (F15: 123 ± 2 and F60: 118 ± 2 mmHg) and dark periods (F15: 136 ± 4 and F60: 136 ± 5 mmHg) compared with controls (light: 111 ± 2 and dark: 117 ± 2 mmHg). SAP variance (VAR) and the low-frequency component (LF) were increased in F15 (>60% and >80%) and F60 (>170% and >140%) compared with C. Cardiac sympatho-vagal balance was enhanced, while baroreflex function was attenuated in fructose groups. Metabolic parameters were unchanged in F15. However, F60 showed significant increases in plasma glucose (26%), cholesterol (44%), triglycerides (22%), insulin (95%), and leptin (63%), as well as glucose intolerance. LF of SAP was positively correlated with SAP. Plasma leptin was correlated with triglycerides, insulin, and glucose tolerance. Results show that increased sympathetic modulation of vessels and heart preceded metabolic dysfunction in fructose-consuming mice. Data suggest that changes in autonomic modulation may be an initiating mechanism underlying the cluster of symptoms associated with cardiometabolic disease.

A proposed fairer method for conducting rofecoxib trials

In this communication, a new plan will be proposed for the conductance of rofecoxib [Vioxx] trials because the current system of individual trials is considered to be irretrievably flawed and grossly unfair. The ideas about rofecoxib trials stem from a different paradigm to explain COX-2 inhibitor (coxib)-induced myocardial infarctions. This model for coxibs is based on the position that coxib-induced infarctions basically are "regular" infarctions, and thus differs from the apparent current position that coxib-induced infarctions are a "special" type of infarction. Three major problems with the current system of rofecoxib trials are proposed: presently used methods of separating out rofecoxib-induced infarctions are invalid, it is difficult to separate out with surety the half of rofecoxib-related infarctions which are rofecoxib-induced, and determining together at rofecoxib trials the two issues of whether an infarction is rofecoxib-induced and whether Merck handled rofecoxib properly leads to unfairness. The new plan bypasses these problems by bypassing the issue of determining at trial whether individual infarctions are rofecoxib-induced. In essence, the plan is a voluntary process designed to result in a class settlement. Plaintiffs are benefited mainly because they do not have to establish individually whether their infarctions are rofecoxib. Merck would benefit because its voluntary acceptance of the plan would be in accord with Merck's position it acted ethically with rofecoxib, and the plan has several factors to reduce significantly the overall level of recompense.

A pathogenetic mechanism for COX-2 inhibitor-induced cardiovascular events proposed to be useful in structuring medical testimony in rofecoxib trials

In this communication, a pathogenetic mechanism for COX-2 inhibitor (coxib)-induced cardiovascular events, especially myocardial infarction, will be discussed. This mechanism is proposed to be useful in structuring medical testimony in rofecoxib trials, and specific principles for separating rofecoxib-induced infarctions from the overall group of rofecoxib-related infarctions will be outlined. The proposed mechanism is based on the principles of the altered homeostatic theory, whose basic positions will be summarized. Coxib-induced infarctions apparently have been considered to be "special" infarctions because they generally are attributed to thromboxane rather than to dyslipidemia. However, it is asserted that coxib-induced infarctions basically are "regular" infarctions because the risk of thromboxane is basically the same as the risk of multiple and diverse "regular" risk factors. Both coxibs and "regular" risk factors are considered to express thrombosis/vasoconstriction, and it is this expression which makes coxib-induced infarctions basically "regular" infarctions. Thrombosis/vasoconstriction is crucial to the induction of myocardial infarction; thrombosis is the accepted and spasm (of resistance vessels) is a proposed mechanism for infarction. It also is asserted that coxib-induced infarctions have a significant load of "regular" risk factors, and that the risk of coxibs adds to the risk of "regular" risk factors. The combination of a significant load of "regular" risk factors plus the risk of coxibs is considered necessary to cause a coxib-induced infarction. It will be difficult to separate out with surety many, if not most, cases of rofecoxib-induced infarctions; this is because of the difficulty in assessing the risk imposed by "regular" risk factors vis-à-vis the risk of rofecoxib, and specific problems in separation will be discussed. However, reasonably, infarctions with a short time-to-event tend to be rofecoxib-induced; infarctions which closely follow a new risk factor, as loss of spouse or stress, would rather automatically be attributed to the new risk factor. It then follows that infarctions with a long time-to-event tend to be non-rofecoxib-induced. Additionally, and contrary to past practice, infarctions cannot be designated as non-rofecoxib-induced infarctions because of the presence of a significant load of "regular" risk factors; after all, rofecoxib-induced infarctions reasonably are associated with a significant load of such risk factors.