Dorie W. Schwertz

Oxidative stress and cardiovascular disease in type 2 diabetes: the role of antioxidants and pro-oxidants.

Oxidative stress occurs when there is an imbalance between free radical production and antioxidant capacity. This may be due to increased free radical formation in the body and/or loss of normal antioxidant defenses. Oxidative stress has been associated with the development of cardiovascular disease. The role of antioxidants in the primary and secondary prevention of coronary heart disease is currently under study. Although epidemiologic evidence indicates that antioxidants may decrease cardiovascular risk, clinical trial data are not conclusive. Information regarding the use and benefits of antioxidants in persons with diabetes is limited. Persons with diabetes may be more prone to oxidative stress because hyperglycemia depletes natural antioxidants and facilitates the production of free radicals. In addition, other factors such as homocysteine, insulin resistance, and aging may be contributory. This article highlights landmark clinical trials that have examined the cardioprotective effect of antioxidants. Because these trials have not been designed to study persons with diabetes, and clinical trial data for this group are not available, correlational studies are also presented. Finally, the concept of oxidative stress, the antioxidant and pro-oxidant factors that may contribute to oxidative stress, and the consequences of oxidative stress in persons with type 2 diabetes are presented. Key words: antioxidants, clinical trials,

Detection of salivary oxytocin levels in lactating women.

Oxytocin is a neuropeptide with widespread influence on many physiological and social functions including: labor and birth, lactation, sexual behavior, nurturing maternal behaviors, and stress reduction. However, our understanding of oxytocins roles has been hampered by lack of noninvasive methods for assessing oxytocin levels. The goal of the present study was to assess whether oxytocin could be detected in saliva and whether changes occurred in the pattern of oxytocin release among lactating women from before, at initiation and after breast feeding. Using a prospective repeated measures design, 11 research participants each provided 18 saliva samples during three feeding cycles (before, at initiation and after breast feeding) for two 24-hr data collection periods (Days 1 and 2). Within each day, saliva was collected at late evening, early morning, and late morning. Salivary samples were concentrated fourfold by dehydration prior to analysis and oxytocin was measured in saliva using an enzyme immunoassay (EIA). Salivary oxytocin values, when reconverted to their original levels, ranged from 6.44 to 61.05 pg/ml. Oxytocin values in saliva varied significantly as a function of the breast feeding cycle, but did not show reliable differences as a function of the time of feeding. Oxytocin was highest before feeding, followed by a decrease at initiation of feeding, and an increase at 30 min after feeding. The findings suggest that oxytocin release into saliva increases in anticipation of feedings. This study also supports the potential usefulness of salivary measures of oxytocin as a noninvasive index of changes in this peptide.

The molecular and cellular pathophysiology of heart failure

In the United States, it is estimated that heart failure develops in 465,000 people each year. Heart failure occurs in both men and women and is associated with a high morbidity and mortality rate in both sexes and in all races. Our knowledge of the pathophysiology of heart failure has advanced beyond the cardiorenal-neurohumoral model and now includes changes in myocyte structure and function. Cellular changes in heart failure include myocyte hypertrophy, abnormalities in calcium homeostasis, excitation-contraction coupling, cross-bridge cycling, and changes in the cytoskeletal architecture. Data also indicate that some of these changes are found during the compensated stage of heart failure; whereas other changes are found during overt decompensation and are associated with changes in systolic and diastolic function. The transition from compensated to decompensated heart failure is more than likely related to the overexpression of neurohormones and peptides such as norepinephrine, angiotensin II, and proinflammatory cytokines. The purpose of this article is to review the epidemiology and cellular pathophysiology of heart failure.

Sexual dimorphism in rat left atrial function and response to adrenergic stimulation.

A number of investigations in humans and animals suggest that there may be intrinsic sex-associated differences in cardiac function. Using left atrial preparations from male and female rat hearts, we examined differences in myocardial function and response to adrenergic agonists. Contractile parameters were measured in isolated atria by conventional isometric methods in the absence or presence of isoproterenol or phenylephrine. Responsiveness to Ca2+ was measured in detergent-skinned atrial fibers and actomyosin ATPase activity was measured in isolated myofibrils. Tetanic contractions were generated by treating the atrium with ryanodine followed by high frequency stimulation. Developed force was greater and maximal rates of contraction and relaxation were more rapid in the female atrium. The relationship between Ca2+ concentration and force in both intact atria and detergent-skinned atrial fibers in females fell to the left of that for males. At low Ca2+ concentrations, skinned fibers from female atria generated more force and myofibrils from female atria had higher myosin ATPase activity than males. Tetanic contraction in the presence of high extracellular Ca2+ was greater in female atria. Male atrium had larger inotropic responses to isoproterenol and to phenylephrine, but drug-elicited cAMP and inositol phosphate production did not differ between sexes. The results demonstrate sex-related differences in atrial function that can be partially explained by greater myofibrillar Ca2+-sensitivity in females. A potential contribution of sarcolemmal Ca2+ influx is suggested by greater tetanic contraction in ryanodine-treated female atrium. The larger response of males to adrenergic stimulation does not appear to be explained by higher production of relevant second messengers. Future studies will investigate the role of sex hormones in these sexually dimorphic responses and may indicate a need for gender-specific therapeutic interventions for myocardial dysfunction.

Salivary Cortisol and Behavioral State Responses of Healthy Newborn Infants to Tactile‐Only and Multisensory Interventions

OBJECTIVE To compare changes in stress reactivity (measured via the biomarker salivary cortisol) and behavioral state in healthy newborn infants immediately following 1 of 2 interventions: (1) tactile-only stimulation or (2) a multisensory, auditory, tactile, visual, and vestibular stimulation with a control group. DESIGN A randomized prospective design pilot study. SETTING Normal newborn nurseries of 2 midwestern perinatal centers. PARTICIPANTS Forty healthy newborn infants receiving standard nursing care. METHODS Infants were randomly assigned to receive 15 minutes of tactile-only, auditory, tactile, visual, and vestibular, or no stimulation 30 minutes before feeding. Saliva samples were collected before, immediately following, and 10 minutes postintervention. Behavioral state was judged every minute. RESULTS Tactile-only group infants had the largest increase in cortisol levels, followed by control group infants. In contrast, infants who received the multisensory intervention showed a significant steady decline in cortisol. Asleep was the predominant state for all 3 groups and cry was minimal. CONCLUSIONS Tactile-only stimulation may increase infant stress reactivity while the benefit of the multisensory auditory, tactile, visual, and vestibular intervention may be in the reduction of infant stress reactivity. Interventions appeared to have minimal effect on stress reactivity based on behavioral state.

Cardiovascular risk factors and metabolic syndrome in alcohol- and nicotine-dependent men and women.

Background and Research Objective: Cardiovascular disease (CVD) is a leading cause of mortality among alcohol-dependent people; however, minimal data exist on the CVD risk factor profile in this high-risk population. The purpose of this study was to examine the prevalence and clustering of traditional and novel CVD risk factors, including components of the metabolic syndrome, in nicotine- and alcohol-dependent adults. Subjects and Methods: Participants (n = 46; 61% men; 87% white), who were a consecutive series of eligible adults (19-56 years of age; mean, 34.8 ± 1.4 years; Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-classified alcoholic; abstinent for ≤7 days), were assessed on entry to a residential drug treatment facility. Cardiovascular disease risk factors were measured using standardized protocols and interview-administered, self-report inventories adapted from epidemiological studies. Dyslipidemia and metabolic syndrome were identified using Adult Treatment Panel III criteria; hypertension was classified by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure criteria. Enzymatic, colorimetric, and immunochemiluminometric techniques were used to measure plasma lipids, homocysteine, and high-sensitivity C-reactive protein, respectively. Results and Conclusions: Dyslipidemia was identified in 74% of participants; 54% were overweight or obese (body mass index, ≥25 kg/m2); 61% were physically inactive (<1,000 kcal/wk); and 61% had some form of hypertension. In addition, 54% had increased homocysteine values; high-sensitivity C-reactive protein was elevated in 28%; and 22% of the participants met criteria for metabolic syndrome. In this study of the CVD risk profile among alcoholics, subjects were found to have an average of 3 CVD risk factors in addition to cigarette smoking. This prevalence and clustering of potentially modifiable risk factors in young, nicotine-dependent alcoholics indicate the need for aggressive risk reduction focused on prevention of CVD.

Alterations in phospholipid metabolism in the globally ischemic rat heart: Emphasis on phosphoinositide specific phospholipase C activity

The effect of global ischemia on myocardial ventricular membrane phospholipids was evaluated using a modified Langendorff preparation. Isolated rat hearts were perfused at 37 degrees C with oxygenated Krebs Ringer solution or rendered ischemic by cessation of perfusion (10 min to 3 h). Longer periods of ischemia were assessed by incubating preperfused (10 min) intact hearts in non-oxygenated Krebs (37 degrees C) for 6 to 18 h. Ischemia-induced alterations in phosphatidylinositol levels and phosphoinositide-specific phospholipase C (PI PLC) activity were assessed in detail, since inositol phospholipids and PI-PLC play putative roles in the regulation of cell function and Ca2+ homeostasis. Decreases in major membrane phospholipids (phosphatidylcholine, phosphatidylserine, cardiolipin and sphingomyelin) were demonstrated after long ischemic periods (6 to 18 h). While periods of ischemia (3 h or less) induced no change in structural phospholipids, an elevation in lysophosphatidylcholine and free fatty acids was found by 1 h. Notably a significant increase in phosphatidylinositol content and an accompanying decrease in cytosolic PI PLC activity was detected by 30 mins of ischemia. Reduced enzymic activity was not due to altered in vitro activation or deactivation of PI-PLC, to a change in the Ca2+ requirement of the enzyme, or to translocation of the enzyme from the cytosol to a membrane fraction. The isolated rat heart made globally ischemic for 30 mins under conditions described for this investigation shows signs of irreversible injury i.e. increased cell Ca2+ content and inability to initiate and maintain rhythmic contraction upon reperfusion. Therefore, it is possible that altered phosphoinositide metabolism may contribute to the evolution of ischemia-elicited irreversible cell injury.

Calcium sensitivity and the effect of the calcium sensitizing drug pimobendan in the alcoholic isolated rat atrium.

We compared the effect of inotropic interventions (isoproterenol and pimobendan) and the relation between Ca2+ and isometric twitch force in atrial muscle from control rats and rats that had consumed alcohol for 2 months. At extracellular Ca2+ concentrations of 1-4 mM, alcohol atria developed less force than the controls. The median effective concentration (EC50) for extracellular Ca2+ was 3.2 +/- 0.01 mM for the alcohol group and 2.8 +/- 0.001 mM for the control group, whereas at maximal Ca2+, developed force was the same in both groups. To test whether the myofilament response to Ca2+ is altered with chronic alcohol consumption, we measured the relation between Ca2+ and force of atrial fiber bundle preparations extracted with Triton X-100. The Ca2+-force relation of alcohol atria (EC50 = 2.4 +/- 0.001 microM) was significantly shifted to the right of that of the control atria (EC50 = 1.94 +/- 0.001 microM Ca2+). Compared with controls, the alcohol atria demonstrated a significant depression in the inotropic effect of the beta-adrenergic agonist isoproterenol over a broad concentration range (10(-9)-10(-6) M). We also tested the effect of pimobendan, an inotropic agent with both phosphodiesterase-inhibiting and myofilament Ca2+-sensitizing actions. Developed force at concentrations of pimobendan <75 microM was similar between groups. However, at concentrations of pimobendan >75 microM, the developed force in alcohol atria was significantly less than control. Our results indicate that 2 months of alcohol consumption is associated with decreases in myofilament Ca2+ sensitivity and altered responsiveness to different inotropic agents.

An Exploratory Study of Neurohormonal Responses of Healthy Men to Massage

OBJECTIVE This research examined the relationship between plasma oxytocin (OT), arginine vasopressin (AVP), cortisol, and anxiety before, during, and after a massage in healthy adult men. DESIGN A randomized, controlled, crossover, repeated-measures, prospective experimental design with subjects acting as their own controls was used. SETTING The research was conducted at a Midwestern University. SUBJECTS Fourteen (14) healthy men between the ages of 19 and 45 years of age were randomly assigned to the order of two conditions: a 20-minute massage (experimental condition) or a 20-minute reading period (control condition). METHODS Blood samples were collected at time intervals during each data collection session. Plasma OT, AVP, and cortisol levels were evaluated by enzyme immunoassay (EIA). The Spielberger State Anxiety Inventory (SAI) and autonomic measures were recorded pre- and postcondition. RESULTS Both experimental (massage) and control (reading) conditions elicited a significant increase in plasma OT levels (p < 0.05) and a decrease in SAI score (p < 0.05) from pre- to postintervention. A significant positive correlation was detected between plasma AVP and plasma cortisol (r = 0.63, n = 24, p = 0.001) in the massage group, whereas a significant positive correlation between plasma AVP and the SAI (r = 0.47, n = 25, p = 0.016) was observed in the reading group. No significant differences were observed for the autonomic measures between conditions. CONCLUSIONS The finding that plasma OT levels increased in both the massage and reading groups, suggests that tactile stimulus is not necessary for OT release. The results suggest that another unknown factor associated with reduction of anxiety may be involved.

Chronic ethanol consumption decreases the phorbol ester binding to membranal but not cytosolic protein kinase C in rat brain

We examined the effect of 60 days of ethanol treatment on protein kinase C (PKC) in membrane and cytosolic fractions of the rat cerebral cortex. Membranal and cytosolic PKC were determined by binding technique using [3H]-phorbol 12,13 dibutyrate (PDBU) as radioligand and phorbol 12-myristate 13-acetate (PMA) as displacer. Chronic ethanol consumption resulted in a decrease in the maximum number of binding sites (Bmax) of [3H]-PDBU binding to membranal PKC without significant change in the apparent dissociation constant (KD) in the rat cortex. We also observed that chronic ethanol consumption had no significant effect on Bmax or KD of [3H]-PDBU binding to cytosolic PKC in the rat cerebral cortex. These results suggest that chronic ethanol consumption leads to the down-regulation of brain PKC associated with membrane but not with cytosol.