Timing of umbilical cord clamping among infants born at 22 through 27 weeks' gestation.

OBJECTIVE: To investigate the safety, feasibility and efficacy of delayed cord clamping (DCC) compared with immediate cord clamping (ICC) at delivery among infants born at 22 to 27 weeks' gestation. STUDY DESIGN: This was a pilot, randomized, controlled trial in which women in labor with singleton pregnancies at 22 to 27 weeks' gestation were randomly assigned to ICC (cord clamped at 5 to 10 s) or DCC (30 to 45 s). RESULTS: Forty mother-infant pairs were randomized. Infants in the ICC and DCC groups had mean gestational ages (GA) of 24.6 and 24.4 weeks, respectively. No differences were observed between the groups across all available safety measures, although infants in the DCC group had higher admission temperatures than infants in the ICC group (97.4 vs. 96.2 °F, P=0.04). During the first 24 h of life, blood pressures were lower in the ICC group than in the DCC group (P<0.05), despite a threefold greater incidence of treatment for hypotension (45% vs. 12%, P<0.01). Infants in the ICC group had increased numbers of red blood transfusions (in first 28 days of life) than infants in DCC group (4.1±3.9 vs. 2.8±2.2, P=0.04). CONCLUSION: Among infants born at an average GA of 24 weeks', DCC appears safe, logistically feasible, and offers hematological and circulatory advantages compared with ICC. A more comprehensive appraisal of this practice is needed.

Early versus delayed umbilical cord clamping in infants with congenital heart disease: a pilot, randomized, controlled trial.

OBJECTIVE: Delayed umbilical cord clamping (DCC) at birth may provide a better neonatal health status than early umbilical cord clamping (ECC). However, the safety and feasibility of DCC in infants with congenital heart disease (CHD) have not been tested. This was a pilot, randomized, controlled trial to establish the safety and feasibility of DCC in neonates with CHD. STUDY DESIGN: Pregnant women admitted >37 weeks gestational age with prenatal diagnosis of critical CHD were enrolled and randomized to ECC or DCC. For ECC, the umbilical cord was clamped <10 s after birth; for DCC, the cord was clamped ~120 s after delivery. RESULTS: Thirty infants were randomized at birth. No differences between the DCC and ECC groups were observed in gestational age at birth or time of surgery. No differences were observed across all safety measures, although a trend for higher peak serum bilirubin levels (9.2±2.2 vs 7.3±3.2 mg dl(-1), P=0.08) in the DCC group than in the ECC group was noted. Although similar at later time points, hematocrits were higher in the DCC than in the ECC infants during the first 72 h of life. The proportion of infants not receiving blood transfusions throughout hospitalization was higher in the DCC than in the ECC infants (43 vs 7%, log-rank test P=0.02). CONCLUSION: DCC in infants with critical CHD appears both safe and feasible, with fewer infants exposed to red blood cell transfusions than with ECC. A more comprehensive appraisal of this practice is warranted.

Effects of hyperoxia on postnatal intestinal development.

Fetuses develop in a marked hypoxic environment in utero. Premature infants often require high concentrations of oxygen to survive and develop in an environment that would be considered an oxygen stress for the fetus. Postnatal hyperoxia alters organ development, but there is minimal research regarding the role of hyperoxia in intestinal development. We attempted to determine whether postnatal hyperoxia exposure alters intestinal growth and function by using a reliable, objective and sensitive set of methods to study region-specific postnatal intestinal maturation. Rat pups born naturally were placed in continual exposure to room air (normoxia) or 85% oxygen (hyperoxia) immediately after birth. Pups were sacrificed at 1 and 2 weeks of age. Intestines were removed and fixed in formalin. Average mucosal, submucosal, and muscularis thicknesses were measured on hematoxylin and eosin stained sections. Immunohistochemistry was performed using antibodies against NOS II. The staining intensity was determined and quantified for site-specific regions of intestinal sections. No differences in mucosal thickness, submucosal thickness, or muscularis thickness were measured in the duodenum, jejunum or colon at any age. At two weeks of age, the thickness of the ileal mucosa was significantly greater in the group reared in 85% oxygen, and the group exposed to room air demonstrated significantly greater NOS II protein concentration than the hyperoxia group within the distal villus, proximal villus/crypts, submucosa, and muscularis in the distal small intestine.

Innervation and connexin isoform expression during diabetes-related bladder dysfunction: early structural vs. neuronal remodelling.

Urinary bladder dysfunction is a major complication in diabetes mellitus and its mechanism has been attributed to altered neurological function (autonomic and/or peripheral neuropathy). Previous studies have demonstrated impaired nerve deficiencies, including either loss of nerve function and/or anatomical loss of neuromuscular nerve terminals. While the phenomenon of diabetes-related neurological injury is well recognised, its pathogenesis is not well understood. Using a well established rat model of diabetes (streptozotocin model), we investigated the prevalence of sympathetic and parasympathetic nerves and relative prevalence of connexin isoforms (gap junction proteins) during diabetes-related bladder dysfunction. Immunohistochemistry and digital image analysis was used to detect the prevalence of postsynaptic neuronal markers, NOS1 and connexin isoform expressions. Immunohistochemistry showed significant increases in tyrosine hydroxylase (marker of sympathetic innervation) and decreased vesicular acetylcholine transporter (marker of parasympathetic innervation), predominantly in the smooth muscle layer, 3 days after diabetes induction, when compared to age-matched controls. Time-dependent and cell-specific decreases in the connexin 43 isoform, but transient increases in connexin 32 and 26, were also observed in diabetic rats vs. controls (p<0.05). These data suggest that selective and time-dependent expression of gap junction proteins and altered prevalence of sympathetic/parasympathetic innervation are early events during diabetes-related bladder dysfunction and remodelling.

Differences in lower extremity alignment between males and females. Potential predisposing factors for knee injury.

AIM: The goal of this study was to compare measures of lower extremity alignment between males and females, which may account for gender differences in anterior cruciate ligament injury rates. Static lower extremity alignment has been implicated as predisposing individuals to anterior cruciate ligament injury and may vary between males and females. An initial step in identifying relevant risk factors for injury is to determine those factors that vary between genders. METHODS: Thirty male and 27 female college aged individuals with no history of lower extremity injury participated. Three indices of lower extremity alignment were measured on each subject: quadriceps angle, thigh foot angle, and subtalar joint range of motion ratio. RESULTS: Q-angles in females exceeded values for males by 4.4 degrees (p<0.001). Thigh foot angle for females was 3.6 degrees greater than for males (p=0.020). Subtalar joint movement ratio did not vary between genders (p=0.573). CONCLUSION: Previous research suggests that abnormal alignment may predispose individuals to anterior cruciate ligament injury. The present findings may help to explain the difference in anterior cruciate ligament injury rates between males and females. Any tangible links between lower extremity alignment and anterior cruciate ligament injury rates must be confirmed with prospective studies.

Distribution of melanin-concentrating hormone neurons projecting to the medial mammillary nucleus.

The melanin-concentrating hormone and neuropeptide glutamic acid-isoleucine are expressed in neurons located mainly in the hypothalamus that project widely throughout the CNS. One of the melanin-concentrating hormone main targets is the medial mammillary nucleus, but the exact origin of these fibers is unknown. We observed melanin-concentrating hormone and neuropeptide glutamic acid-isoleucine immunoreactive fibers coursing throughout the mammillary complex, showing higher density in the pars lateralis of the medial mammillary nucleus, while the lateral mammillary nucleus showed sparse melanin-concentrating hormone innervation. The origins of these afferents were determined by using implant of the retrograde tracer True Blue in the medial mammillary nucleus. Double-labeled neurons were observed in the lateral hypothalamic area, rostromedial zona incerta and dorsal tuberomammillary nucleus. A considerable population of retrogradely labeled melanin-concentrating hormone perikaryal profiles was also immunoreactive to neuropeptide glutamic acid-isoleucine (74+/-15% to 85+/-15%). The afferents from the lateral hypothalamic area, rostromedial zona incerta and dorsal tuberomammillary nucleus to the medial mammillary nucleus were confirmed using implant of the anterograde tracer Phaseolus vulgaris leucoagglutinin. In addition, using double-labeled immunohistochemistry, we found no co-localization between neurons expressing melanin-concentrating hormone and adenosine deaminase (histaminergic marker) in the dorsal tuberomammillary nucleus. We hypothesize that these melanin-concentrating hormone projections participate in spatial memory process mediated by the medial mammillary nucleus. These pathways would enable the animal to look for food during the initial moments of appetite stimulation.

Time-dependent urinary bladder remodeling in the streptozotocin-induced diabetic rat model.

Urinary bladder dysfunction and remodeling are well-recognized phenomena in diabetes but detailed assessments of tissue morphological changes have not been conducted. We studied time-dependent morphological changes in bladders from diabetic rats (streptozotocin model) and evaluated the usefulness of automated digital imaging technology as an unbiased, reproducible, and convenient method for the bladder morphometric analysis. Urinary bladders were isolated from diabetic (3 days, 2 weeks or 5 weeks after single injection of streptozotocin, 65 mg/kg) or control rats (0 or 5 weeks) and were processed for histochemical evaluations (hematoxylin/eosin and Mason's trichrome staining). Digital image analysis was used to quantify equatorial cross-sectional areas of bladder tissue and lumen, as well as relative prevalence of the three primary tissue components viz. smooth muscle, urothelium, and extracellular matrix. Digital imaging and color segmentation provided reliable and unbiased evaluations of the bladder tissue sections. Progressive increases in total bladder tissue and lumen area were observed in the diabetic animals relative to controls (p<0.05), demonstrating classic hypertrophy and dilation. Prevalence of smooth muscle and urothelium (% of total tissue) both increased significantly, but collagen content decreased. Average bladder wall thickness and urothelium thickness were unchanged. Bladder remodeling during experimental diabetes is associated with time-dependent chamber dilation and increased tissue mass. Changes in bladder wall composition also occurred in a time-dependent manner, most notably increased smooth muscle and urothelium and decreased collagen prevalence. Furthermore, automated digital imaging technologies provide an unbiased, reproducible, and convenient method for detailed morphometric analysis of bladder tissues.

C-reactive protein elevation in patients with atrial arrhythmias: inflammatory mechanisms and persistence of atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) may persist due to structural changes in the atria that are promoted by inflammation. C-reactive protein (CRP), a marker of systemic inflammation, predicts cardiovascular events and stroke, a common sequela of AF. We hypothesized that CRP is elevated in patients with atrial arrhythmias. METHODS AND RESULTS: Using a case-control study design, CRP in 131 patients with atrial arrhythmias was compared with CRP in 71 control patients. Among arrhythmia patients, 6 had frequent atrial ectopy or tachycardia, 86 had paroxysmal AF, 39 had persistent AF lasting >30 days, and 70 had lone arrhythmias. CRP was higher in arrhythmia than in control patients (median, 0.21 versus 0.096 mg/dL; P<0.001). Arrhythmia patients in AF within 24 hours before sampling had higher CRP than those in sinus rhythm (0.30 versus 0.15 mg/dL; P<0.001). CRP in controls was not different than in patients with atrial ectopy or tachycardia. Lone arrhythmia patients had a CRP of 0.21 mg/dL, which was not significantly lower than arrhythmia patients with structural heart disease (CRP, 0.23 mg/dL) but higher than controls (P=0.002). Persistent AF patients had a higher CRP (0.34 mg/dL) than paroxysmal AF patients (0.18 mg/dL; P=0.008); both groups had higher CRP levels than controls (P

Ascorbate attenuates atrial pacing-induced peroxynitrite formation and electrical remodeling and decreases the incidence of postoperative atrial fibrillation.

Atrial fibrillation (AF), the most common chronic arrhythmia, increases the risk of stroke and is an independent predictor of mortality. Available pharmacological treatments have limited efficacy. Once initiated, AF tends to self-perpetuate, owing in part to electrophysiological remodeling in the atria; however, the fundamental mechanisms underlying this process are still unclear. We have recently demonstrated that chronic human AF is associated with increased atrial oxidative stress and peroxynitrite formation; we have now tested the hypothesis that these events participate in both pacing-induced atrial electrophysiological remodeling and in the occurrence of AF following cardiac surgery. In chronically instrumented dogs, we found that rapid (400 min(-1)) atrial pacing was associated with attenuation of the atrial effective refractory period (ERP). Treatment with ascorbate, an antioxidant and peroxynitrite decomposition catalyst, did not directly modify the ERP, but attenuated the pacing-induced atrial ERP shortening following 24 to 48 hours of pacing. Biochemical studies revealed that pacing was associated with decreased tissue ascorbate levels and increased protein nitration (a biomarker of peroxynitrite formation). Oral ascorbate supplementation attenuated both of these changes. To evaluate the clinical significance of these observations, supplemental ascorbate was given to 43 patients before, and for 5 days following, cardiac bypass graft surgery. Patients receiving ascorbate had a 16.3% incidence of postoperative AF, compared with 34.9% in control subjects. In combination, these studies suggest that oxidative stress underlies early atrial electrophysiological remodeling and offer novel insight into the etiology and potential treatment of an enigmatic and difficult to control arrhythmia. The full text of this article is available at http://www.circresaha.org.

Diabetes related cardiomyopathy time dependent echocardiographic evaluation in an experimental rat model.

Type I diabetes is associated with a unique form of cardiomyopathy in the absence of atherosclerosis. The mechanisms involved in this phenomenon are not defined, but in humans this is associated with initial diastolic dysfunction followed by altered contractile performance. A relevant animal model would provide opportunities for mechanistic studies and experimental therapeutics, but none have been previously established for this unique form of cardiac pathophysiology, particularly with respect to clinically relevant and time-dependent diastolic and systolic assessments. Here we tested the hypothesis that the streptozotocin rat model mimics human phenomena with respect to time-dependent diastolic and systolic performance deficits, and investigated a role for cardiac hypertrophy and/or fibrosis. Streptozotocin was dosed 65 mg/kg i.p. and cardiac performance was assessed longitudinally for 56 days using noninvasive echocardiographic techniques. Significant hyperglycemia was detected within 3 days and remained elevated throughout the study (p<0.05). Significant reductions in HR and diastolic performance (transmitral flow velocities and slopes) were observed within 3 days relative to age matched controls, and these reductions progressed throughout the 56 day study. In contrast, statistically significant systolic dysfunction (LV fractional shortening, cardiac output) and LV dilation were detected only after 35 days. Increases in LV size and/or extent of fibrosis were not observed at any time. These results demonstrate the value of echocardiographic methods for time-dependent diastolic and systolic assessments in rodent models. Furthermore, diastolic dysfunction precedes contractile abnormalities in the streptozotocin model, similar to events that occur in humans.

Non-invasive echocardiographic studies in mice: influence of anesthetic regimen.

Transgenic murine models of cardiovascular disease offer great potential insights regarding mechanisms of human disease, but efficient and reliable methods for phenotype evaluation are necessary. We employed non-invasive echocardiography to evaluate hemodynamic parameters in mice, and evaluated statistical reliability of these parameters with respect to anesthesia regimen. Male CF-1 mice received inhaled halothane (0.25-0.75% in 95% O2) or ketamine/xylazine (80/10 mg/kg i.p.) and 2-dimensional, M-mode, and Doppler ultrasound imaging were used to assess cardiac contractility and aortic flow velocities. Halothane was more convenient and reliable with respect to rate of induction, reversal, and control of anesthetic depth. At comparable levels of anesthesia, ketamine/xylazine produced significant reductions in heart rate (308 +/- 14 vs. 501 +/- 14 bpm, p<0.001), left ventricular fractional shortening (41.7 +/- 1.3 vs. 49.3 +/- 1.0%, p<0.001), and cardiac output (7.6 +/- 0.5 vs. 11.5 +/- 0.6 ml/min, p<0.001) when compared to halothane inhalation. No change in stroke volume or peak aortic velocity was observed. Correlation analyses revealed highly significant positive relationships between heart rate and fractional shortening (r=0.61, p<0.002) and cardiac output (r=0.88, p<0.001) but no relation to stroke volume or aortic velocity. Variability of intra-animal and intragroup parameter estimation were frequently 2-fold larger for ketamine/xylazine anesthesia vs. halothane. Statistical power analysis showed the increased measurement error for ketamine/xylazine leads to much larger numbers of mice/group to achieve identical statistical sensitivity. These data further illustrate the feasibility of echocardiography for rapid, non-invasive cardiovascular assessment in mice. However, several obtainable parameters are highly sensitive to both heart rate and anesthetic used and the choice and control of anesthetic are critical for physiologically relevant performance parameters and maximal ability to detect statistical differences among groups. Thus, for these non-invasive studies, inhalation anesthesia with agents such as halothane is superior to anesthesia induced by ketamine/xylazine administration.

Impaired myofibrillar energetics and oxidative injury during human atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is associated with severe contractile dysfunction and structural and electrophysiological remodeling. Mechanisms responsible for impaired contractility are undefined, and current therapies do not address this dysfunction. We have found that myofibrillar creatine kinase (MM-CK), an important controller of myocyte contractility, is highly sensitive to oxidative injury, and we hypothesized that increased oxidative stress and energetic impairment during AF could contribute to contractile dysfunction. Methods and Results-- Right atrial appendages were obtained from AF patients undergoing the Maze procedure and from control patients who were in normal sinus rhythm and undergoing cardiac surgery. MM-CK activity was reduced in AF patients compared with controls (25.4+/-3.4 versus 18.2+/-3.8 micromol/mg of myofibrillar protein per minute; control versus AF; P<0.05). No reduction in total CK activity or myosin ATPase activity was detected. This selective reduction in MM-CK activity was associated with increased relative expression of the beta-myosin isoform (25+/-6 versus 63+/-5%beta, CTRL versus AF; P<0.05). Western blotting of AF myofibrillar isolates demonstrated no changes in protein composition but showed increased prevalence of protein oxidation as detected by Western blotting for 3-nitrotyrosine (peroxynitrite biomarker) and protein carbonyls (hydroxyl radical biomarker; P<0.05). Patterns of these oxidative markers were distinct, which suggests discrete chemical events and differential protein vulnerabilities in vivo. MM-CK inhibition was statistically correlated to extent of nitration (P<0.01) but not to carbonyl presence. CONCLUSIONS: The present results provide novel evidence of oxidative damage in human AF that altered myofibrillar energetics may contribute to atrial contractile dysfunction and that protein nitration may be an important participant in this condition.

Therapeutic implications of human endothelial nitric oxide synthase gene polymorphism.

Vascular endothelial dysfunction is now recognized as a common phenomenon in an array of cardiovascular disorders. Production of nitric oxide via the endothelial isoform of nitric oxide synthase [eNOS (previously termed NOS3 or ecNOS)] is vital for a healthy endothelium; several polymorphic variations of the gene encoding eNOS (NOS3) are now known and have been investigated with respect to disease risk. Surprisingly, only approximately half of these studies have demonstrated significant associations between NOS3 polymorphisms and cardiovascular disease, and many reports are contradictory. Central issues include adequate statistical power, appropriateness of control cohorts, multigene interactions and plausible biological consequences. So far, the inconsistencies are not unique to the NOS3 polymorphisms, but probably represent the broad challenges in defining genetic aspects of complex disease processes.

Inositol hexakisphosphate kinase 2 mediates growth suppressive and apoptotic effects of interferon-beta in ovarian carcinoma cells.

Interferons (IFNs) regulate the expression of genes that mediate their antiviral, antitumor, and immunomodulatory actions. We have previously shown that IFN-beta suppresses growth of human ovarian carcinoma xenografts in vivo and induces apoptosis of ovarian carcinoma cells in vitro. To investigate mechanisms of IFN-beta-induced apoptosis we employed an antisense technical knockout approach to identify gene products that mediate cell death and have isolated several regulators of interferon-induced death (RIDs). In this investigation, we have characterized one of the RIDs, RID-2. Sequence analysis revealed that RID-2 was identical to human inositol hexakisphosphate kinase 2 (IP6K2). IP6K2 is post-transcriptionally induced by IFN-beta in ovarian carcinoma cells. A mutant IP6K2 with substitutions in the putative inositol phosphate binding domain abrogates IFN-beta-induced apoptosis. These studies identify a novel function for IP6K2 in cell growth regulation and apoptosis.

Free 3-nitrotyrosine causes striatal neurodegeneration in vivo.

Peroxynitrite formation has been demonstrated in several neurodegenerative disorders; thus far, protein nitration and consequent alterations in protein function are implicated as mechanistic events. Free 3-nitrotyrosine (free-3NT) is also elevated in these settings; a neurotoxic role for this modified amino acid has not been investigated. We tested the hypothesis that free-3NT is neurotoxic in vivo, using a mouse model of striatal degeneration. The neurodegenerative effects of the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA) (unilateral intrastriatal injection, 64 nmol) were compared with free-3NT (32 nmol) or free-tyrosine (free-TYR) (32 nmol). 6-OHDA-treated mice exhibited significant ipsilateral turning behavior after d-amphetamine challenge, indicative of unilateral striatal injury (ipsilateral-contralateral turning differential, 21.1 +/- 6.8). Significant turning behavior was also observed in free-3NT-treated mice but not in free-tyrosine-treated mice (free-3NT, 16.0 +/- 3.9; free-TYR, 1 +/- 2.7; p < 0.01). Immunohistochemistry was used to evaluate striatal tyrosine hydroxylase (TH) content. 6-OHDA or free-3NT treatment caused severe reductions in TH immunoreactivity in injected striata compared with the contralateral hemisphere (injected/contralateral immunoreactivity ratio: 6-OHDA, 0.23 +/- 0.07; free-3NT, 0.49 +/- 0.02). Free-tyrosine treatment had no effect (1.03 +/- 0.09). Turning behavior was correlated with striatal TH ratio (p < 0.01). Furthermore, we observed a striking unilateral reduction in TH-positive cell body counts in the substantia nigra pars compacta of 6-OHDA- and free-3NT-treated mice (injected/contralateral cell count ratio: 6-OHDA, 0.40 +/- 0.04; free-3NT, 0.59 +/- 0.02). Free-tyrosine treatment had no effect (1.05 +/- 0.04). No evidence for increased striatal protein incorporation of 3NT was observed in any treatment group. These data represent the first evidence that free-3NT can elicit neurodegenerative effects in vivo; free-3NT may have a causal role in neurodegenerative conditions.

Oxidative pathways in cardiovascular disease: roles, mechanisms, and therapeutic implications.

Despite some recent declines, cardiovascular disease (CVD) remains the major cause of death in the United States and worldwide. Most recent advances in the treatment of CVD states have been produced by inhibition of mechanisms involved in disease progress. Many studies conducted in the last decade have illustrated increased biological oxidative pathways during CVD in animals and humans. Thus, increased production of reactive oxygen species may be a unifying mechanism in CVD progression, and antioxidants may have therapeutic value in this setting. In this review we address the following questions: Do oxidative mechanisms play a role in CVD? Where do the oxidants come from? What are the relevant oxidative events? What are the therapeutic implications?

Perineurium inflammation and altered connexin isoform expression in a rat model of diabetes related peripheral neuropathy.

Diabetes related peripheral neuropathy involves both somatic and autonomic nerves and leads to an array of debilitating abnormalities. Mechanisms may include decreased neuronal conductance, reactive oxygen species, and decreased performance of the perineurium blood-nerve barrier. Here we studied the perineurium characteristics of the dorsal penile nerve in a rat model of diabetes related peripheral neuropathy. Immunohistochemistry showed extensive and perineurial cell-specific nitric oxide synthase2 staining in diabetic animals as compared to age matched controls (P<0.05); however no apparent difference in immunostaining pattern was observed for 3-nitrotyrosine (a stable biomarker of peroxynitrite formation). Significant reductions in connexins 32 and 26 were seen in the diabetic perineurium with no detectable levels of connexin 43 in either control or diabetic dorsal nerve. These data provide new evidence of perineurial cell inflammatory responses and altered gap junction protein expression during diabetes related neuropathies and suggests that strategies to protect this cell type may have therapeutic value.

Structural and spectroscopic studies of the versatile coordination chemistry of the chiral ligand N,N-bis(1-propan-2-onyl oxime)-L-methionine N'-methylamide with Ni(II) and Zn(II).

The potentially pentadentate, chiral ligand N,N-bis(1-propan-2-onyl oxime)-L-methionine N'-methylamide (L-MABO) shows remarkable versatility in its coordination chemistry with Ni(II) and Zn(II). In the crystal structure of the ZnCl2 complex of L-MABO, the ligand coordinates to the metal only through its three nitrogen donor groups (one amine and two oximes), with two chloride anions completing the distorted trigonal bipyramidal coordination sphere. In the NiCl2 complex, the three nitrogen donors and the thioether sulfur coordinate, along with two chlorides. The crystal structure of the Ni(NO3)2 complex contains two independent molecules, one of which coordinates the three nitrogens, the thioether sulfur, and the amide oxygen of L-MABO in addition to one nitrate anion. The second molecule coordinates the three nitrogen donors, the amide oxygen, one nitrate anion, and a methanol molecule. Thus, in only three crystal structures, L-MABO demonstrates its ability to provide N3, N3S, N3O, and N3OS donor sets. The thioether-bound complexes are unusual in that they have a predominantly nitrogen environment with a nickel-thioether bond that is not constrained by surrounding donor groups in a macrocyclic or linear polydentate motif. Comparison of the thioether-coordinated and methanol-coordinated molecules in the Ni(NO3) salt of L-MABO demonstrate the effect of the thioether bond on the relative "hardness" of the nickel. The electronic absorption and circular dichroism spectra of the aqueous solutions of the nickel complexes are interpreted in terms of a "descent in symmetry" model based on successive C3v and Cs distortions from octahedral geometry. These ligand field spectra indicate that in aqueous solution all ligand groups except for the three nitrogens of L-MABO are displaced by water. In acetonitrile, the non-nitrogen donors in the nitrate salt may also be displaced, while the chlorides remain coordinated.

Peroxynitrite induced nitration and inactivation of myofibrillar creatine kinase in experimental heart failure.

OBJECTIVE: Oxidative stress is implicated in the initiation and progression of congestive heart failure, but the putative reactive species and cellular targets involved remain undefined. We have previously shown that peroxynitrite (ONOO(-), an aggressive biological oxidant and nitrating agent) potently inhibits myofibrillar creatine kinase (MM-CK), a critical controller of contractility known to be impaired during heart failure. Here we hypothesized that nitration and inhibition of MM-CK participate in cardiac failure in vivo. METHODS: Heart failure was induced in rats by myocardial infarction (left coronary artery ligation) and confirmed by histological analysis at 8 weeks postinfarct (1.3+/-1.4 vs. 37.7+/-3.2% left ventricular circumference; sham control vs. CHF, n=10 each). RESULTS: Immunohistochemistry demonstrated significantly increased protein nitration in failing myocardium compared to control (optical density: 0.58+/-0.06 vs. 0.93+/-0.09, sham vs. CHF, P<0.05). Significant decreases in MM-CK activity and content were observed in failing hearts (MM-CK k(cat): 6.0+/-0.4 vs. 3.0+/-0.3 micromol/nM M-CK/min, P<0.05; 6.8+/-1.3 vs. 4.7+/-1.2% myofibrillar protein, P<0.05), with no change in myosin ATPase activity. In separate experiments, isolated rat cardiac myofibrils were exposed to ONOO(-) (2-250 microM) and enzyme studies were conducted. Identical to in vivo studies, selective reductions in MM-CK were observed at ONOO(-) concentrations as low as 2 microM (IC(50)=92.5+/-6.0 microM); myosin ATPase was unaffected with ONOO(-) concentrations as high as 250 microM. Concentration dependent nitration of MM-CK occurred and extent of nitration was statistically correlated to extent of CK inhibition (P<0.001). Immunoprecipitation of MM-CK from failing left ventricle yielded significant evidence of tyrosine nitration. CONCLUSION: These data demonstrate that cardiac ONOO(-) formation and perturbation of myofibrillar energetic controllers occur during experimental heart failure; MM-CK may be a critical cellular target in this setting.

Impact forces and neck muscle activity in heading by collegiate female soccer players.

Three soccer header types (shooting, clearing and passing) and two heading approaches (standing and jumping) were manipulated to quantify impact forces and neck muscle activity in elite female soccer players. The 15 participants were Division I intercollegiate soccer players. Impact forces were measured by a 15-sensor pressure array secured on the forehead. The electromyographic (EMG) activity of the left and right sternocleidomastoid and trapezius muscles was recorded using surface electrodes. Maximum impact forces and impulses as well as the EMG data were analysed with separate repeated-measures analyses of variance. Impact forces and impulses did not differ among the header types or approaches. Higher values were found for jumping versus standing headers in the mean normalized EMG for the right sternocleidomastoid. In addition, the integrated EMG was greater for the right sternocleidomastoid and right and left trapezius (P < 0.05). The sternocleidomastoid became active earlier than the trapezius and showed greater activity before ball contact. The trapezius became active just before ball contact and showed greater activity after ball contact. The increased muscle activity observed in the neck during the jumping approach appears to stabilize the connection between the head and body, thereby increasing the stability of the head-neck complex.