Rapid protein identification using direct infusion nanoelectrospray ionization mass spectrometry

Current protein identification techniques are largely based on MALDI-TOF mass fingerprinting and LC-ESI MS/MS sequence tag analysis. Here we describe an improved method for rapid protein identification that uses direct infusion nanoelectrospray quadrupole time-of-flight (nanoESI QTOF) MS. Protein digests were analyzed without LC separation using nanoESI on a QSTAR XL MS/MS system in information dependent data acquisition mode. The protein identification conditions and parameters were extensively evaluated with in-solution and in-gel digested protein samples. Rapid identification of proteins was achieved and compared directly to the results obtained on the same samples using nanoflow HPLC-MS/MS on the QSTAR system. The increased throughput, reproducibility, the high data quality, and the ease of use make the direct infusion system an efficient and affordable technique for protein identification analysis.     

Chronic enhancement of brain oxytocin levels causes enduring anti-aggressive and pro-social explorative behavioral effects in male rats

Oxytocin (OXT) has been implicated in the regulation of social behaviors, including intermale offensive aggression. Recently, we showed that acute enhancement of brain OXT levels markedly suppressed offensive aggression and increased social exploration in resident rats confronted with an intruder in their home territory. Moreover, a different responsivity to the exogenous OXTergic manipulation was observed among individuals based on their baseline aggression. In this study we aimed at evaluating the behavioral response to chronically enhancing or attenuating central OXT levels, and at scrutinizing whether the trait-aggression moderates the treatment-induced behavioral changes. To this end, resident male wild-type Groningen rats were continuously (via osmotic minipumps) intracerebroventricularly infused with synthetic OXT or a selective OXT receptor (OXTR) antagonist for 7 days. Changes in behavior were assessed performing a resident–intruder test before and at the end of the treatment period, as well as after 7 days of withdrawal. Chronic infusion of OXT was found to selectively suppress aggression and enhance social exploration. Chronic blockage of OXTRs instead increased introductory aggressive behavior (i.e. lateral threat), yet without affecting the total duration of the aggression. The magnitude of the anti-aggressive changes correlated positively with the level of baseline aggression. Interestingly, OXT-induced behavioral changes persisted 7 days after cessation of the treatment. In conclusion, these findings provide further evidence that enhanced functional activity of the central OXTergic system decreases social offensive aggression while it increases social explorative behavior. The data also indicate that chronically enhancing brain OXT levels may cause enduring anti-aggressive and pro-social explorative behavioral effects.     

Action of anorexigenic peptide injected into the brain: Dissociation of effect on body weight and feeding in the rat

Previous reports on the effect of anorexigenic peptide (AXP) administered systemically in the rodent are inconsistent in terms of the effect of the tri-peptide on food intake and body weight. The purpose of this study was to examine the effect of AXP infused into the brain on these measures. In post-pubescent female rats of the Sprague-Dawley strain, guide cannulae were permanently implanted in the lateral cerebral ventricle for repeated intracerebroventricular (ICV) infusion. Postoperatively, measures of food and water intake and body weight were obtained every day at the same time. After a 7-day base-line period, AXP was infused bilaterally in a total volume of 15 μl and in a dose of either 0.25 μg (n=7) or 1.25 μg (n=5), with artificial CSF vehicle serving as the control solution (n=6). ICV infusions were given once daily for 20 consecutive days, after which the same intake and body weight measures were recorded for another 7-day period. The rats given 0.25 μg AXP showed a significant suppression in weight gain with the overall slope of the growth curve being 0.358. In contrast, the growth slope of the rats given the 1.25 μg dose of AXP was 0.621, whereas those given the CSF was 0.823. Although the trends of intake of food tended to follow the curves of the rats' body weight, the difference between g/kg food intake of rats during ICV infusions of either dose of AXP was not significantly different from that of the CSF controls. Water intake also was unaffected by either dose of AXP. These results demonstrate that this tri-peptide derived from urine of patients afflicted with anorexia nervosa exerts a direct effect on the brain. Since the 0.25 μg dose of AXP infused acutely ICV caused a sustained hyperthermia, its mechanism of action is apparently a metabolic one; that is, the interruption in the gain in body weight of the rat is independent of the amount of food it ingests.     

3D Wettable Framework for Dendrite‐Free Alkali Metal Anodes

The infinite volume change and dendritic behavior in alkali metal anodes lead to low Coulombic efficiency and short‐circuit issues that significantly hamper renewed efforts at commercialization. Here, a dendrite‐free alkali metal anode, made by thermally preloading molten Li or Na into a 3D framework with high alkali wettability, is reported. In the mechanically robust 3D framework, carbon fiber (CF) serves as an electrical highway that provides fast charge transfer for the redox reaction. Through a facile solution‐based process, a SnO₂ coating is introduced to modify the poor wetting behavior of the carbon framework and drastically improve both the electrochemical performance and reliability. The kinetic barrier to adhesion of molten alkali metals on the CF framework is eliminated by the mixed reaction with SnO₂. The growth of dendrites is effectively repressed under the decreased local current density of the 3D framework. In full‐cell configurations with LiFePO₄ cathodes, the Li–CF electrode shows reduced polarization and 90% capacity retention after 500 cycles in traditional carbonate electrolyte. Comparable improvements are also observed in 3D electrodes for Na metal batteries. These findings on a stable 3D carbon framework with improved wetting behavior provide significant practical implications for achieving safe and commercially viable alkali metal anodes.     

A porcine animal model to mimic the restart of enteral nutrition (refeeding-model)

With the aim towards establishing an animal model of total parenteral nutrition (TPN), 12 piglets aged 9 weeks (mean body weight 21 kg) were surgically provided with central venous catheters. Six piglets were nourished parenterally with the objective to reach a 14-d period of TPN; the other six piglets served as control and were fed normally. Only one animal from each group could be monitored over the whole period. Nine piglets were euthanised on d 13 and one on d 12. No animal showed fever or signs of septicaemia during the study. The levels of Ca, Mg, Na and P in the blood were within the normal range as were those for blood glucose and plasma creatinine. Symptoms of the TPN included: transient diarrhoea, occasional appearance of faecal blood and occasional absence of defecation. A reduced small intestine length and altered mucosal morphology and function were observed. One animal showed bile stasis at the end of the study. All TPN animals showed a remarkably high level of blood urea early in the morning. The intestinal symptoms observed may resemble the human situation during TPN. However, due to the fast growth rate, pigs aged 9 weeks have higher nutrient requirements per kg body weight. Consequently, the osmolality of the nutrient solution was necessarily high. Whether the significantly higher blood urea observed in the TPN group reflected a catabolic metabolism during the starving period at night-time could not be conclusively shown. Alternatively, it could reflect a slower growth rate and a resulting quantitative excess of amino acids (AA), or could have been the consequence of a suboptimal AA composition. A permanent infusion would be favourable in order not to overcharge the capacity for glucose uptake and amino acid metabolism during the infusion.     

植入式输液港的临床应用

目的探讨植入式输液港的护理方法和体会。方法对我科11例患者进行植入输液港,对植入方法、护理技术、常见问题进行研究、总结。结果植入式输液港解决了患者频繁输液的痛苦,减轻了护士的工作量。结论植入式输液港提高了护理安全性,应广泛推广并规范这一新技术。     

American Association of Clinical Endocrinology Clinical Practice Guideline: The Use of Advanced Technology in the Management of Persons With Diabetes Mellitus

ObjectiveTo provide evidence-based recommendations regarding the use of advanced technology in the management of persons with diabetes mellitus to clinicians, diabetes-care teams, health care professionals, and other stakeholders.MethodsThe American Association of Clinical Endocrinology (AACE) conducted literature searches for relevant articles published from 2012 to 2021. A task force of medical experts developed evidence-based guideline recommendations based on a review of clinical evidence, expertise, and informal consensus, according to established AACE protocol for guideline development.Main Outcome MeasuresPrimary outcomes of interest included hemoglobin A1C, rates and severity of hypoglycemia, time in range, time above range, and time below range.ResultsThis guideline includes 37 evidence-based clinical practice recommendations for advanced diabetes technology and contains 357 citations that inform the evidence base.RecommendationsEvidence-based recommendations were developed regarding the efficacy and safety of devices for the management of persons with diabetes mellitus, metrics used to aide with the assessment of advanced diabetes technology, and standards for the implementation of this technology.ConclusionsAdvanced diabetes technology can assist persons with diabetes to safely and effectively achieve glycemic targets, improve quality of life, add greater convenience, potentially reduce burden of care, and offer a personalized approach to self-management. Furthermore, diabetes technology can improve the efficiency and effectiveness of clinical decision-making. Successful integration of these technologies into care requires knowledge about the functionality of devices in this rapidly changing field. This information will allow health care professionals to provide necessary education and training to persons accessing these treatments and have the required expertise to interpret data and make appropriate treatment adjustments.     

Can mesenchymal stem cells reduce vulnerability of dopaminergic neurons in the substantia nigra to oxidative insult in individuals at risk to Parkinson's disease?

PD (Parkinson's disease) is characterized by the selective loss of DA (dopaminergic) neurons in the substantia nigra of the midbrain region, but not in the ventral tegmental area and other catecholaminergic cell group areas. The aetiology of PD is attributed both to environmental and genetic causes, and certain population of individuals may be classified as at risk of developing PD later in life. However, there are as yet no therapy regimens that can help to delay or prevent the onset of the disease to realize long-term benefits from this early diagnosis. In PD, a vicious cycle gets initiated in the substantia nigra, because of which susceptible neurons continue to degenerate whereas damaged neurons do not get enough support for regeneration. This happens primarily because of the local environment of oxidative damage brought about by the dual presence of dopamine and high levels of iron, decline in cellular detoxification systems and low density of glial cells surrounding the DA neurons in the mesencephalic region. To enhance the defence mechanism of the substantia nigra in this situation, it is necessary to combat the oxidative insult while providing trophic factors for the survival and regeneration of the damaged neurons. In light of in vitro and in vivo studies, MSCs (mesenchymal stem cells) as candidates for cell-based therapies in PD have greater scope than as mere replacement of cell type, since they can be used as a cellular system for the detoxification of ROS (reactive oxygen species) as well as a supplier of neurotrophic factors to modulate the local environment. Building on progress in unravelling the multipronged effect of MSCs, we therefore hypothesize that MSCs could be used as a prophylactic strategy to delay or prevent the onset of PD in at-risk individuals, and to slow down the progression of the disease.     

Arterial acid-base status during digestion and following vascular infusion of NaHCO(3) and HCl in the South American rattlesnake, Crotalus durissus

Digestion is associated with gastric secretion that leads to an alkalinisation of the blood, termed the "alkaline tide". Numerous studies on different reptiles and amphibians show that while plasma bicarbonate concentration ([HCO(3)(-)](pl)) increases substantially during digestion, arterial pH (pHa) remains virtually unchanged, due to a concurrent rise in arterial PCO(2) (PaCO(2)) caused by a relative hypoventilation. This has led to the suggestion that postprandial amphibians and reptiles regulate pHa rather than PaCO(2). Here we characterize blood gases in the South American rattlesnake (Crotalus durissus) during digestion and following systemic infusions of NaHCO(3) and HCl in fasting animals to induce a metabolic alkalosis or acidosis in fasting animals. The magnitude of these acid-base disturbances were similar in magnitude to that mediated by digestion and exercise. Plasma [HCO(3)(-)] increased from 18.4+/-1.5 to 23.7+/-1.0 mmol L(-1) during digestion and was accompanied by a respiratory compensation where PaCO(2) increased from 13.0+/-0.7 to 19.1+/-1.4 mm Hg at 24 h. As a result, pHa decreased slightly, but were significantly below fasting levels 36 h into digestion. Infusion of NaHCO(3) (7 mmol kg(-1)) resulted in a 10 mmol L(-1) increase in plasma [HCO(3)(-)] within 1 h and was accompanied by a rapid elevation of pHa (from 7.58+/-0.01 to 7.78+/-0.02). PaCO(2), however, did not change following HCO(3)(-) infusion, which indicates a lack of respiratory compensation. Following infusion of HCl (4 mmol kg(-1)), plasma pHa decreased by 0.07 units and [HCO(3)(-)](pl) was reduced by 4.6 mmol L(-1) within the first 3 h. PaCO(2), however, was not affected and there was no evidence for respiratory compensation. Our data show that digesting rattlesnakes exhibit respiratory compensations to the alkaline tide, whereas artificially induced metabolic acid-base disturbances of same magnitude remain uncompensated. It seems difficult to envision that the central and peripheral chemoreceptors would experience different stimuli during these conditions. One explanation for the different ventilatory responses could be that digestion induces a more relaxed state with low responsiveness to ventilatory stimuli.     

Effects of a seven-day continuous infusion of ropivacaine on circadian rhythms in the rat

The present study was conducted to evaluate the effect of a 7 d continuous infusion of ropivacaine on the 24 h rhythms of body temperature, heart rate, and locomotor activity. After an initial 7 d baseline, rats were randomly divided into two groups of 4 rats each to receive ropivacaine or saline via an osmotic pump for 7 consecutive days. The pumps were removed thereafter and observed during a 7 d recovery span. The studied circadian rhythms were measured by radiotelemetry throughout each of the 7 d periods. An additional group of 4 rats was studied under the same experimental conditions to assess the plasma levels of ropivacaine on days 3 and 8 following pump implantation. Our results indicate that ropivacaine does not induce loss of the circadian rhythms of body temperature, heart rate, or locomotor activity; a prominent period of 24 h was found for all variables in all animals, before, during, and after ropivacaine treatment. However, ropivacaine treatment did modify some characteristics of the rhythms; it increased the MESOR (24 h mean) of the heart rate and locomotor activity rhythms and advanced the acrophase (peak time) of the locomotor activity circadian rhythm. The present study indicates that the circadian rhythms of heart rate and locomotor activity are modified after continuous infusion of ropivacaine, which is of particular interest, given the potential cardiotoxicity of this local anesthetic agent.