Hexamethyldisiloxane-based nanoprobes for (1) H MRI oximetry

Quantitative in vivo oximetry has been reported using ¹⁹F MRI in conjunction with reporter molecules, such as perfluorocarbons, for tissue oxygenation (pO₂). Recently, hexamethyldisiloxane (HMDSO) has been proposed as a promising alternative reporter molecule for ¹H MRI‐based measurement of pO₂. To aid biocompatibility for potential systemic administration, we prepared various nanoemulsion formulations using a wide range of HMDSO volume fractions and HMDSO to surfactant ratios. Calibration curves (R₁ versus pO₂) for all emulsion formulations were found to be linear and similar to neat HMDSO for low surfactant concentrations (< 10% v/v). A small temperature dependence in the calibration curves was observed, similar to previous reports on neat HMDSO, and was characterized to be approximately 1 Torr/ °C under hypoxic conditions. To demonstrate application in vivo, 100 µL of this nanoemulsion was administered to healthy rat thigh muscle (Fisher 344, n = 6). Dynamic changes in mean thigh tissue pO₂ were measured using the PISTOL (proton imaging of siloxanes to map tissue oxygenation levels) technique in response to oxygen challenge. Changing the inhaled gas to oxygen for 30 min increased the mean pO₂ significantly (p < 0.001) from 39 ± 7 to 275 ± 27 Torr. When the breathing gas was switched back to air, the tissue pO₂ decreased to a mean value of 45 ± 6 Torr, not significantly different from baseline (p > 0.05), in 25 min. A first‐order exponential fit to this part of the pO₂ data (i.e. after oxygen challenge) yielded an oxygen consumption‐related kinetic parameter k = 0.21 ± 0.04 min^?1. These results demonstrate the feasibility of using HMDSO nanoemulsions as nanoprobes of pO₂ and their utility to assess oxygen dynamics in vivo, further developing quantitative ¹H MRI oximetry. Copyright © 2011 John Wiley & Sons, Ltd.     

Primary Structure of the Ovine Hypothalamic Luteinizing Hormone-Releasing Factor (LRF)

The primary structure of ovine hypothalamic hypophysiotropic luteinizing hormone-releasing factor, LRF, has been established as pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH(2) by hydrolysis of the peptide with chymotrypsin or pyrrolidone-carboxylylpeptidase and by analysis of the products by an Edman-dansylation sequencing technique, as well as by mass spectrometry of the derived phenylthiohydantoins. A decapeptide with the proposed primary structure, prepared by total synthesis, gave the same result on sequencing. The synthetic decapeptide possesses the same biological activities as the native ovine LRF. The amino-acid sequence of ovine LRF is identical to that already published for porcine LRF.     

Chest compression depth and survival in out-of-hospital cardiac arrest

Aim

Outcomes from out-of-hospital cardiac arrest (OHCA) may improve if rescuers perform chest compressions (CCs) deeper than the previous recommendation of 38–51 mm and consistent with the 2010 AHA Guideline recommendation of at least 51 mm. The aim of this study was to assess the relationship between CC depth and OHCA survival.

Methods

Prospective analysis of CC depth and outcomes in consecutive adult OHCA of presumed cardiac etiology from two EMS agencies participating in comprehensive CPR quality improvement initiatives. Analysis: Multivariable logistic regression to calculate adjusted odds ratios (aORs) for survival to hospital discharge and favorable functional outcome.

Results

Among 593 OHCAs, 136 patients (22.9%) achieved return of spontaneous circulation, 63 patients (10.6%) survived and 50 had favorable functional outcome (8.4%). Mean CC depth was 49.8 ± 11.0 mm and mean CC rate was 113.9 ± 18.1 CC min⁻¹. Mean depth was significantly deeper in survivors (53.6 mm, 95% CI: 50.5–56.7) than non-survivors (48.8 mm, 95% CI: 47.6–50.0). Each 5 mm increase in mean CC depth significantly increased the odds of survival and survival with favorable functional outcome: aORs were 1.29 (95% CI 1.00–1.65) and 1.30 (95% CI 1.00–1.70) respectively.

Conclusion

Deeper chest compressions were associated with improved survival and functional outcome following OHCA. Our results suggest that adhering to the 2010 AHA Guideline-recommended depth of at least 51 mm could improve outcomes for victims of OHCA.     

Platelet activation and secretion in patients with major depression,thoracic aortic atherosclerosis,or renal dialysis treatment

Relatively little is known concerning the magnitude of alterations of platelet activation and secretion markers of patients with major depression when compared to patients at increased risk for, or with current, clinically significant atherosclerosis. Markers of in vivo platelet stimulation and secretion were measured under basal conditions in normal comparison subjects (n = 12) and three patient groups: patients diagnosed with DSM-IV major depression (n = 15), dialysis-dependent patients (n = 12), and patients with severe thoracic aortic atherosclerosis (n = 10). In comparison to normal comparison subjects, depressed patients and patients with thoracic aortic atherosclerosis exhibited the greatest platelet stimulation as detected by increased anti-LIBS platelet binding. Dialysis-dependent patients exhibited the highest plasma concentrations of the renally-excreted platelet-specific secretion protein, beta-thromboglobulin. This study extends previous observations of increased platelet activation in patients with major depression and documents similar alterations in patients with transesophageal echocardiography (TEE)-documented thoracic aortic atherosclerosis. Future studies will determine whether the magnitude of platelet stimulation and secretion in patients with comorbid depression and atherosclerotic aortic disease is greater than that observed in nondepressed patients with atherosclerotic aortic disease or major depression alone. These findings provide further evidence for either increased platelet activation and/or intrinsic heightened platelet reactivity as one of the biological substrates underlying the increased risk of depressed patients for cardiovascular disease.     

Concept analysis of self‐mutilation

Title. Concept analysis of self‐mutilation. Aim. This paper is a report of a concept analysis to define and describe self‐mutilation. Background. Although there has been an increased interest in self‐mutilation, as evidenced by recent publication of opinion literature, anecdotal reports and a few clinical studies, the concept has not been well developed to guide nursing research and interventions. Method. Definitions and uses of self‐mutilation were obtained in a comprehensive review of the health, psychology and education literature up to April 2007 to identify the defining attributes, antecedents and consequences. Walker and Avant’s concept analysis strategy was the organizing framework. Findings. Self‐mutilation is the intentional act of tissue destruction with the purpose of shifting overwhelming emotional pain to a more acceptable physical pain. Antecedents of self‐mutilation are impaired coping skills and an unhealthy response to situations that cause unbearable emotional stress. Limited research suggests that risk factors for self‐mutilation may be White race, adolescent age, female sex and history of sexual abuse as a child. Although self‐mutilation allows the individual to gain control over emotions and provides a diversion from emotional pain, a release of endorphins after the physical damage that contributes to the feeling of relief supports an addictive maladaptive coping cycle of pain, relief, shame and self‐hate. Conclusion. The theoretical definition of the concept of self‐mutilation offers the basis for nurses to develop interventions to provide competent care when discovering injuries that are self‐inflicted.     

Weight gain and psychiatric treatment: is there as role for green tea and conjugated linoleic acid?

Dietary supplement use is widespread in developed nations. In particular, patients who utilize mental health services also report frequent consumption of dietary supplements, often in relation to management of adverse events and specifically weight gain. Weight gain induced by psychotropic medications can further compound psychological distress and negatively influence compliance. Here we report on four cases of social anxiety disorder treated with the atypical antipsychotic quetiapine. Self-administration of conjugated linoleic acid and green tea extract may have influenced objective anthropomorphic measurements; each patient had an unexpected decrease in total body fat mass, a decrease in body fat percentage and an increase in lean body mass. Since weight gain is a common and undesirable side-effect with psychiatric medications, our observation strongly suggests the need for controlled clinical trials using these agents.     

Primary Structure of Somatostatin, A Hypothalamic Peptide That Inhibits the Secretion of Pituitary Growth Hormone

Somatostatin, a peptide isolated from ovine hypothalamic tissue that inhibits the release of radioimmunoassayable growth hormone in vitro from rat or human pituitary cells or in vivo in rats, has the primary structure [Formula: see text]. The structure was established by submitting the carboxymethylated peptide, the carboxymethylated tryptic digest, and the chymotryptic digest of the peptide to Edman degradation. Degradation products were analyzed by amino-acid analysis, as well as in some cases by determination of N-termini by dansylation or by determination of phenylthiohydantoins by mass spectrometry.