Cognitive Deficits in Executive and Language Functions Predict Postoperative Delirium

OBJECTIVES

Postoperative delirium (POD) remains the most common complication in older adults, with cognitive impairment being the main risk factor. Patients with mild cognitive impairment, in particular, have much to lose from delirium; despite this, their cognitive impairment might be clinically overlooked. Understanding which cognitive domains are particularly predictive in this regard may improve the sensitivity of preoperative testing and allow for a more targeted application of resource-intensive measures to prevent delirium in the perioperative period. The authors conducted this study with the aim of identifying the most indicative cognitive domains.

DESIGN

A secondary analysis of a randomized controlled trial.

SETTING

At a single center, the University Medical Centre Hamburg in Hamburg, Germany.

PARTICIPANTS

Patients ≥60 years without major neurocognitive disorders (dementia, Mini-Mental State Examination score ≤23) scheduled for cardiovascular surgery.

MEASUREMENTS AND MAIN RESULTS

Preoperative neuropsychologic testing and delirium screening were performed twice daily until postoperative day 5. A multiple logistic regression model was applied to determine the predictive ability of test performances for the development of delirium.

RESULTS

A total of 541 patients were included in the analysis; the delirium rate was 15.6%. After controlling for confounders, only low performance within the Trail Making Test B/A (odds ratio [OR] = 1.32; 95% CI: 1.05-1.66) and letter fluency (OR = 0.66; 95% CI: 0.45-0.96) predicted a particularly high risk for delirium development. The discriminative ability of the final multiple logistic regression model to predict POD had an area under the curve of 0.786.

CONCLUSIONS

Impairment in the cognitive domains of executive function and language skills associated with memory, inhibition, and access speed seem to be particularly associated with the development of delirium after surgery in adults ≥65 years of age without apparent preoperative neurocognitive impairment.

Tumor cell E-selectin ligands determine partialefficacy of bortezomib on spontaneous lung metastasis formation of solid human tumors in vivo

Extravasation of circulating tumor cells (CTCs) is critical for metastasis and is initiated by adhesive interactions between glycoligands on CTCs and E-selectin on endothelia. Here, we show that the clinically approved proteasome inhibitor bortezomib (BZM; Velcade) counteracts the cytokine-dependent induction of E-selectin in the lung mediated by the primary tumor, thereby impairing endothelial adhesion and thus spontaneous lung metastasis in vivo. However, the efficacy of BZM crucially depends on the tumor cells' E-selectin ligands, which determine distinct adhesion patterns. The canonical ligands sialyl-Lewis A (sLeA) and sLeX mediate particularly high-affinity E-selectin binding so that the incomplete E-selectin-reducing effect of BZM is not sufficient to disrupt adhesion or metastasis. In contrast, tumor cells lacking sLeA/X nevertheless bind E-selectin, but with low affinity, so that adhesion and lung metastasis are significantly diminished. Such low-affinity E-selectin ligands apparently consist of sialylated MGAT5 products on CD44. BZM no longer has anti-metastatic activity after CD44 knockdown in sLeA/X-negative tumor cells or E-selectin knockout in mice. sLeA/X can be determined by immunohistochemistry in cancer samples, which might aid patient stratification. These data suggest that BZM might act as a drug for inhibiting extravasation and thus distant metastasis formation in malignancies expressing low-affinity E-selectin ligands.

Comparison of the '4-item assessment test' and 'nursing delirium screening scale' delirium screening tools on non-intensive care unit wards: A prospective mixed-method approach

BACKGROUND

In elderly patients following surgery, postoperative delirium (POD) is the most frequent complication and is associated with negative outcomes. The 2017 European Society of Anaesthesiology guideline on POD aims to improve patient care by implementing structured delirium prevention, diagnosis and treatment. However, these recommendations, especially systematic delirium screening, are still incompletely adopted in clinical practice. The aim of this study was to evaluate the feasibility and acceptance of validated delirium screening tools and to identify barriers to their implementation on nonintensive care unit wards.

METHODS

Screening rates, as well as practicability, acceptance and the interprofessional handling of positive results, were assessed for each group. Screening rates were calculated as a percentage of the total potential testing episodes completed (up to 15 per patient). Patients were considered eligible when aged 65 years and above. Barriers and motivating factors were assessed in a mixed method approach by utilising questionnaires and focus group discussions.

INTERVENTION

In a 3-month phase, a guideline-compliant screening protocol involving screening for POD three times daily for 5 days following surgery was introduced in five wards: both the 4-item assessment test (4AT) and the nursing delirium screening scale (NuDESC) were used. Before commencing the study and again after 6 weeks, medical staff of the respective wards underwent a 45 min training session.

RESULTS

Of a total of 3183 potential testing episodes, 999 (31.4%) were completed, with more NuDESC observational tests (43%) than 4AT bedside tests completed (20%). The 4AT was considered more difficult to integrate into daily working routines, it took longer to administer, and nurses felt uncomfortable conducting the screening (53 vs. 13%). Screening results indicating delirium were often not discussed within the team (47%), and nurses felt that often such results were not taken seriously by physicians (54%).

CONCLUSION

The observational NuDESC showed a higher completion rate than the bedside 4AT, although overall testing rates were low. The necessary time needed to conduct the screening, the negative reactions by patients, insufficient team communication and a lack of initiation of any therapy were identified as major barriers in the implementation of the guideline-compliant screening protocol. For all staff, further education and awareness of the importance of POD diagnosis and treatment might improve the screening rates. The NuDesc received better results concerning acceptance, practicability and introduction into daily work routine, leading to higher screening rates compared with the 4AT. The latter instrument, which was intended to be used rather selectively or when POD is suspected, might therefore not be suitable for guideline-compliant regular and repeated screening for POD.

Pharmaceutical management of elderly high-risk patients in perioperative settings (PHAROS): protocol of a pilot sequential intervention study

INTRODUCTION

With increasing age, the risk of complications after surgery rises in elderly patients. Furthermore, the prevalence of multimorbidity and polypharmacy rises with age, making this elderly population especially vulnerable for drug-related problems and posing an additional risk for postoperative complications. Still, only few studies have concentrated on investigating how medication safety can be improved in these patients. The aim of this pilot study is to examine the impact of a comprehensive intervention (interprofessional systematic medication therapy management) on medication appropriateness in elderly polymedicated, multimorbid patients during hospital stay for elective surgery.

METHODS AND ANALYSIS

This pilot study will include a total number of 140 patients. Surgical high-risk patients ≥65 years taking more than five chronic systemic drugs will be recruited consecutively for 9 months in the control group capturing usual care regarding medication history and in-hospital medication therapy management without any study intervention. Recruitment of the intervention group will be conducted for another 9 months. The intervention consists of the following components: an additional medication history by a hospital pharmacist before admission, a subsequent medication review, optimisation of the long-term medication and recommendations to the patient's general practitioner. A follow-up will be performed 3 months after surgery. As the primary study outcome, medication appropriateness will be measured using the Medication Appropriateness Index.Secondary outcomes are postoperative complications, incidence and frequency of adverse drug reactions and potentially inappropriate medication in the elderly, satisfaction with inpatient and outpatient care, medication reconciliation and health-related quality of life. Multivariable analyses will be used to analyse all quantitative research questions.

ETHICS AND DISSEMINATION

Ethics approval was obtained by the medical ethics committee of the Medical Chamber of Hamburg (study ID: PV5754). Data will be published in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

The study is registered at www.drks.de: DRKS00014621.

Improvement of perioperative care of the elderly patient (PeriAge): protocol of a controlled interventional feasibility study

INTRODUCTION

Geriatric patients have a pronounced risk to suffer from postoperative complications. While effective risk-specific perioperative measures have been studied in controlled experimental settings, they are rarely found in routine healthcare. This study aims (1) to implement a multicomponent preoperative and intraoperative intervention, and investigate its feasibility, and (2) exploratorily assess the effectiveness of the intervention in routine healthcare.

METHODS AND ANALYSIS

Feasibility and exploratory effectiveness of the intervention will be investigated in a monocentric, prospective, non-randomised, controlled trial. The intervention includes systematic information for patients and family about measures to prevent postoperative complications; preoperative screening for frailty, malnutrition, strength and mobility with nutrient supplementation and physical exercise (prehabilitation) as needed. Further components focus on potentially inadequate medication, patient blood-management and carbohydrate loading prior to surgery, retainment of orientation aids in the operating room and a geriatric anaesthesia concept. Data will successively be collected from control, implementation and intervention groups. Patients aged 65+ with impending surgery will be included. A sample size of 240, n=80 per group, is planned. Assessments will take place at inclusion and 2, 30 and 180 days after surgery. Mixed-methods analyses will be performed. Exploratory effectiveness will be assessed using mixed segmented regressions. The primary endpoint is functional status. Secondary endpoints include cognitive performance, health-related quality of life, length of inpatient stay and occurrence of postoperative complications. Feasibility will be assessed through semi-structured interviews with staff and patients and quantitative analyses of the data quality, focussing on practicability, acceptance, adoption and fidelity to protocol.

ETHICS AND DISSEMINATION

The study will be carried out in accordance with the Helsinki Declaration and to principles of good scientific practice. The Ethics Committee of the Medical Association Hamburg, Germany, approved the protocol (study ID: PV5596). Results will be disseminated in scientific journals and healthcare conferences.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT03325413.

Determinants of Perioperative Outcome in Frail Older Patients

BACKGROUND

Older patients are undergoing surgery in increasing numbers. Frailty is a key risk factor associated with higher rates of complications and mortality, longer hospital stays, and functional impairment.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed, including guidelines from Germany and abroad.

RESULTS

Many studies have been published on the assessment of frailty and its consequences, but the scientific investigation of this topic and the clinical utility of the findings are made more difficult by the lack of a uniform definition and of uniform instruments for assessment. Some definitions of frailty include only physical aspects, while others encompass cognitive, emotional, and social factors as well. Despite this variability, the assessment of frailty enables better estimation of the perioperative risk so that the patient can be optimally prepared for the operation. Especially for frail elderly patients, an interdisciplinary approach is called for over the entire perioperative treatment period.

CONCLUSION

In the future, the definition of frailty will need to be standardized so that this parameter can be properly assessed and investigated in comparative studies.

The P2-receptor-mediated Ca2+ signalosome of the human pulmonary endothelium - implications for pulmonary arterial hypertension

Dysfunction of the pulmonary endothelium is associated with most lung diseases. Extracellular nucleotides modulate a plethora of endothelial functions in the lung such as vessel integrity, vasodilatation, inflammatory, and thrombotic responses as well as survival and DNA repair, mostly via Ca²⁺ signaling pathways. However, a comprehensive analysis of the molecular components of the underlying P2 receptor-mediated Ca²⁺ signaling pathways in the lung has not been conducted so far. Therefore, our aim was to identify the principal P2 receptor Ca²⁺ signalosome in the human pulmonary endothelium and investigate potential dysregulation in pulmonary vascular disease. Comparative transcriptomics and quantitative immunohistochemistry were performed on publicly available RNA sequencing and protein datasets to identify the specific expression profile of the P2-receptor Ca²⁺ signalosome in the healthy human pulmonary endothelium and endothelial cells (EC) dysfunctional due to loss of or defective bone morphogenetic protein receptor (BMPR2). Functional expression of signalosome components was tested by single cell Ca²⁺ imaging. Comparative transcriptome analysis of 11 endothelial cell subtypes revealed a specific P2 receptor Ca²⁺ signalosome signature for the pulmonary endothelium. Pulmonary endothelial expression of the most abundantly expressed Ca²⁺ toolkit genes CALM1, CALM2, VDAC1, and GNAS was confirmed by immunohistochemistry (IHC). P2RX1, P2RX4, P2RY6, and P2YR11 showed strong lung endothelial staining by IHC, P2X5, and P2Y1 were found to a much lesser extent. Very weak or no signals were detected for all other P2 receptors. Stimulation of human pulmonary artery (HPA) EC by purine nucleotides ATP, ADP, and AMP led to robust intracellular Ca²⁺ signals mediated through both P2X and P2Y receptors. Pyrimidine UTP and UDP-mediated Ca²⁺ signals were generated almost exclusively by activation of P2Y receptors. HPAEC made dysfunctional by siRNA-mediated BMPR2 depletion showed downregulation of 18 and upregulation of 19 P2 receptor Ca²⁺ signalosome genes including PLCD4, which was found to be upregulated in iPSC-EC from BMPR2-mutant patients with pulmonary arterial hypertension. In conclusion, the human pulmonary endothelium expresses a distinct functional subset of the P2 receptor Ca²⁺ signalosome. Composition of the P2 receptor Ca²⁺ toolkit in the pulmonary endothelium is susceptible to genetic disturbances likely contributing to an unfavorable pulmonary disease phenotype found in pulmonary arterial hypertension.

Streptococcus pneumoniae inhibits purinergic signaling and promotes purinergic receptor P2Y2 internalization in alveolar epithelial cells

Bacterial pneumonia is a global health challenge that causes up to 2 million deaths each year. Purinergic signaling plays a pivotal role in healthy alveolar epithelium. Here, we used fluorophore-based analysis and live-cell calcium imaging to address the question of whether the bacterial pathogen Streptococcus pneumoniae directly interferes with purinergic signaling in alveolar epithelial cells. Disturbed purinergic signaling might result in pathophysiologic changes like edema formation and atelectasis, which are commonly seen in bacterial pneumonia. Purine receptors are mainly activated by ATP, mediating a cytosolic calcium response. We found that this purinergic receptor P2Y₂-mediated response is suppressed in the presence of S. pneumoniae in A549 and isolated primary alveolar cells in a temperature-dependent manner. Downstream inositol 3-phosphate (IP₃) signaling appeared to be unaffected, as calcium signaling via protease-activated receptor 2 remained unaltered. S. pneumoniae-induced suppression of the P2Y₂-mediated calcium response depended on the P2Y₂ phosphorylation sites Ser-243, Thr-344, and Ser-356, which are involved in receptor desensitization and internalization. Spinning-disk live-cell imaging revealed that S. pneumoniae induces P2Y₂ translocation into the cytosol. In conclusion, our results show that S. pneumoniae directly inhibits purinergic signaling by inducing P2Y₂ phosphorylation and internalization, resulting in the suppression of the calcium response of alveolar epithelial cells to ATP, thereby affecting cellular integrity and function.

Postoperative Nausea and Vomiting Following Craniotomy: Risk Factors and Complications in Context of Perioperative High-dose Dexamethasone Application

Introduction Postoperative nausea and vomiting (PONV) is common in patients after craniotomy and may lead to severe postoperative complications. The aim of this study was to identify risk factors and postoperative complications associated with PONV in the context of perioperative high-dose dexamethasone administration.

Patients and Methods In this prospective single-center study, all patients planned for elective craniotomy for supra- and infratentorial lesions were eligible to be included. Any PONV in a 24-hour period after craniotomy was recorded and analyzed with regard to time to postoperative complications and the administration of perioperatively administered high-dose dexamethasone.

Results The overall PONV rate of 421 patients during a 9-month period was 18.1% (76 patients). Multivariate analysis revealed a significant association of PONV with female sex, infratentorial localization, age, and history of PONV. There was no association between PONV and postoperative complications such as intracranial hemorrhage, cerebrospinal fluid (CSF) leaks, or pneumonia. Perioperative administration of high-dose dexamethasone for prophylactic prevention of edema was the only significant risk factor for postoperative complications (odds ratio [OR]: 3.34; confidence interval [CI], 1.39–8.05; p < 0.01) with a highly significant association with the occurrence of CSF leaks (OR: 6.85; CI, 1.62–29.05; p < 0.01).

Conclusion The low PONV rate of 18.1% in this study may be the result of the frequent perioperative administration of high-dose dexamethasone for the prevention of edema. Our data indicate that perioperative high-dose dexamethasone is significantly associated with CSF leaks and can therefore not be recommended on a regular basis.

The Perioperative Care of Older Patients

BACKGROUND

Elderly patients are a growing and vulnerable group with an elevated perioperative risk. Perioperative treatment pathways that take these patients' special risks and requirements into account are often not implemented in routine clinical practice.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed, the AWMF guideline database, and the Cochrane database for guidelines from Germany and abroad, meta-analyses, and Cochrane reviews.

RESULTS

The care of elderly patients who need surgery calls for an interdisciplinary, interprofessional treatment concept. One component of this concept is preoperative preparation of the patient ("prehabilitation"), which is best initiated before hospital admission, e.g., correction of deficiency states, optimization of chronic drug treatment, and respiratory training. Another important component consists of pre-, intra-, and postoperative measures to prevent delirium, which can lower the frequency of this complication by 30-50%: these include orientation aids, avoidance of inappropriate drugs for elderly patients, adequate analgesia, early mobilization, short fasting times, and a perioperative nutrition plan. Preexisting cognitive impairment predisposes to postoperative delirium (odds ratios [OR] ranging from 2.5 to 4.5). Frailty is the most important predictor of the postoperative course (OR: 2.6-11). It follows that preoperative assessment of the patient's functional and cognitive status is essential.

CONCLUZION

The evidence-based and guideline-consistent care of elderly patients requires not only close interdisciplinary, interprofessional, and cross-sectoral collaboration, but also the restructuring and optimization of habitual procedural pathways in the hospital. Elderly patients' special needs can only be met by a treatment concept in which the entire perioperative phase is considered as a single, coherent process.

Dead space ventilation promotes alveolar hypocapnia reducing surfactant secretion by altering mitochondrial function

BACKGROUND

In acute respiratory distress syndrome (ARDS), pulmonary perfusion failure increases physiologic dead space ventilation (V_D/V_T), leading to a decline of the alveolar CO₂ concentration [CO₂]_iA. Although it has been shown that alveolar hypocapnia contributes to formation of atelectasis and surfactant depletion, a typical complication in ARDS, the underlying mechanism has not been elucidated so far.

METHODS

In isolated perfused rat lungs, cytosolic or mitochondrial Ca²⁺ concentrations ([Ca²⁺]_cyt or [Ca²⁺]_mito, respectively) of alveolar epithelial cells (AECs), surfactant secretion and the projected area of alveoli were quantified by real-time fluorescence or bright-field imaging (n=3-7 per group). In ventilated White New Zealand rabbits, the left pulmonary artery was ligated and the size of subpleural alveoli was measured by intravital microscopy (n=4 per group). Surfactant secretion was determined in the bronchoalveolar lavage (BAL) by western blot.

RESULTS

Low [CO₂]_iA decreased [Ca²⁺]_cyt and increased [Ca²⁺]_mito in AECs, leading to reduction of Ca²⁺-dependent surfactant secretion, and alveolar ventilation in situ. Mitochondrial inhibition by ruthenium red or rotenone blocked these responses indicating that mitochondria are key players in CO₂ sensing. Furthermore, ligature of the pulmonary artery of rabbits decreased alveolar ventilation, surfactant secretion and lung compliance in vivo. Addition of 5% CO₂ to the inspiratory gas inhibited these responses.

CONCLUSIONS

Accordingly, we provide evidence that alveolar hypocapnia leads to a Ca²⁺ shift from the cytosol into mitochondria. The subsequent decline of [Ca²⁺]_cyt reduces surfactant secretion and thus regional ventilation in lung regions with high V_D/V_T. Additionally, the regional hypoventilation provoked by perfusion failure can be inhibited by inspiratory CO₂ application.

Warum und wie sollte ich Frailty erfassen? – ein Ansatz für die Anästhesieambulanz

Frailty (Gebrechlichkeit) ist eine Einschränkung der physiologischen Reserve bei älteren Patienten mit schwerwiegenden individuellen und sozioökonomischen Folgen. Multiple Aspekte der Patientenbehandlung sowie das Outcome werden durch Frailty nachhaltig beeinflusst. Obwohl mehr als 60 Messinstrumente existieren, sind die Erfassung und Berücksichtigung funktioneller Assessments in der klinischen Routine unzureichend umgesetzt. Das interdisziplinäre und interprofessionelle Verständnis, warum und wie Frailty beurteilt werden sollte, ist die Grundlage für die dauerhafte Implementierung. Der Artikel zeigt die Auswirkungen von Frailty und Vorteile einer Früherkennung auf und gibt einen Überblick über die wichtigsten Instrumente, die in der Frailty-Erkennung und -Bewertung verwendet werden können. Die frühe präoperative Detektion bietet ein vielfältiges Optimierungspotenzial für die peri- und intraoperative Versorgung. Verschiedene Frailty-Assessment-Tools körperlicher, kognitiver und psychosozialer Domänen werden vorgestellt und diskutiert. Frailty-Assessments variieren immens in Bezug auf die erforderliche Zeit, die Ausrüstung und das Fachwissen zur Durchführung. Wir empfehlen mindestens einen Test für die einzelnen Dimensionen von Frailty, um ein holistisches Bild der geriatrischen Patienten zu erhalten. Die Bewertung von Frailty sollte übergreifend in die interdisziplinären Strukturen der klinischen Routine implementiert werden, um die Patientensicherheit sowie das kurz- und langfristige Outcome zu verbessern.

[Preoperative Evaluation and Arrangements: The Elderly Patient]

With a constantly growing portion of elderly within our population and the advances of modern medicine, surgery on aged and very aged patients has become a daily hospital routine. Due to the physical and mental features of ageing these patients face special perioperative risks. They display a higher rate of complications, morbidity and cognitive deficits which might in the end lead to persisting need of care. Even in the healthy elderly, most organ functions are "physiologically" instable or deficient and the homeostasis of health and disease is fragile. The preoperative evaluation of the aged patient has to be extended towards risk factors and pathologic pre-conditions which derive especially from high age and are so far not determined by a mere "fit-for-anaesthesia?"

EVALUATION

This includes assessment of frailty and functional status as well as the evaluation of pre-existing cognitive deficits, malnutrition and polypharmacy. Prevention of postoperative cognitive deficits and delirium is an important goal of medical therapy and requires i. a. omission of benzodiazepines, BIS-controlled anaesthesia, focus on patient's comfort and orientation and inclusion of close relatives and confidants in all processes. Considering all this, an elderly patient might require more time than usually given to be well prepared for anaesthesia, surgery and the postoperative course. The altered physiology and the special risk profile of the aged patient demand special attention and time throughout the perioperative phase. With an increasing number of elderly presenting for surgery, it is likely that more age-adapted structures and processes become implemented in our hospitals.

In vitro and in vivo evidence for an inflammatory role of the calcium channel TRPV4 in lung epithelium: Potential involvement in cystic fibrosis

Cystic fibrosis (CF) is an inherited disease associated with chronic severe lung inflammation, leading to premature death. To develop innovative anti-inflammatory treatments, we need to characterize new cellular and molecular components contributing to the mechanisms of lung inflammation. Here, we focused on the potential role of "transient receptor potential vanilloid-4" (TRPV4), a nonselective calcium channel. We used both in vitro and in vivo approaches to demonstrate that TRPV4 expressed in airway epithelial cells triggers the secretion of major proinflammatory mediators such as chemokines and biologically active lipids, as well as a neutrophil recruitment in lung tissues. We characterized the contribution of cytosolic phospholipase A2, MAPKs, and NF-κB in TRPV4-dependent signaling. We also showed that 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids, i.e., four natural lipid-based TRPV4 agonists, are present in expectorations of CF patients. Also, TRPV4-induced calcium mobilization and inflammatory responses were enhanced in cystic fibrosis transmembrane conductance regulator-deficient cellular and animal models, suggesting that TRPV4 is a promising target for the development of new anti-inflammatory treatments for diseases such as CF.

Mechanotransduction in the lungs

Mechanical ventilation may induce or aggravate lung injury, a phenomenon known as ventilator induced lung injury (VILI). On a macroscopic level, the effects of mechanical stress and strain on lung tissue are well described. Increased tidal volumes may lead to volutrauma, raised airway pressures may cause barotrauma and cyclic collapse and reopening of alveolar units contributes to atelectrauma. These three harmful mechanisms may lead to local and systemic pulmonary inflammatory response known as biotrauma. The purpose of this review was to elucidate fundamental mechanisms involved in the mechanotransduction of mechanical stimuli on a cellular level. Bronchial epithelial cells in the distal airways as well as alveolar epithelial cells are exposed to a variety of mechanical forces. These cells are involved in sensing and translation of mechanical stimuli into an inflammatory response. This review provides insight into current knowledge of cellular and molecular pathways during the process of pulmonary epithelial mechanosensation and mechanotransduction under different mechanical conditions. Since evidence for specific pathways is generally lacking in some fields of alveolar epithelial mechanotransduction, this article aims at providing reasonable hypothesis for further investigation.

Dichloroacetate prevents restenosis in preclinical animal models of vessel injury

Despite the introduction of antiproliferative drug-eluting stents, coronary heart disease remains the leading cause of death in the United States. In-stent restenosis and bypass graft failure are characterized by excessive smooth muscle cell (SMC) proliferation and concomitant myointima formation with luminal obliteration. Here we show that during the development of myointimal hyperplasia in human arteries, SMCs show hyperpolarization of their mitochondrial membrane potential (ΔΨm) and acquire a temporary state with a high proliferative rate and resistance to apoptosis. Pyruvate dehydrogenase kinase isoform 2 (PDK2) was identified as a key regulatory protein, and its activation proved necessary for relevant myointima formation. Pharmacologic PDK2 blockade with dichloroacetate or lentiviral PDK2 knockdown prevented ΔΨm hyperpolarization, facilitated apoptosis and reduced myointima formation in injured human mammary and coronary arteries, rat aortas, rabbit iliac arteries and swine (pig) coronary arteries. In contrast to several commonly used antiproliferative drugs, dichloroacetate did not prevent vessel re-endothelialization. Targeting myointimal ΔΨm and alleviating apoptosis resistance is a novel strategy for the prevention of proliferative vascular diseases.

[Transfusion-related acute lung injury]

Transfusion-related acute lung injury (TRALI) developed into the leading cause of transfusion-related morbidity and mortality after the first description by Popovsky et al. approximately three decades ago. It was the most frequent reason for transfusion-related fatalities worldwide before implementation of risk minimization strategies by donor selection. Plasma-rich blood products, such as fresh frozen plasma and apheresis platelets seem to be the leading triggers of TRALI. Hypoxemia and development of pulmonary edema within 6 h of transfusion are the diagnostic criteria for TRALI. The differentiation between cardiac failure and other transfusion-related lung injuries, such astransfusion-associated circulatory overload ( TACO) is difficult and causal treatment is not available. Therapy is based on supportive measures, such as oxygen insufflationor mechanical ventilation. The exactly pathogenesis is still unknown but the most propagated hypothesis is the two-event-model. Neutrophils are primed by the underlying condition, e.g. sepsis or trauma during the first event and these primed neutrophils are activated by transfused leukoagglutinating antibodies (immunogen) or bioreactive mediators (non-immunogen) during the second-event. Transfusion of leukoagglutinating antibodies from female donors with one or more previous pregnancies is the most frequent reason. No more TRALI fatalities were reported after implementation of the donor selection in Germany in 2009.

[When the resting membrane potential becomes restless. Acute hyperkalemia in the perioperative phase]

Acute hyperkalemia is a life-threatening event and often occurs abruptly and without warning in the perioperative field. Risk factors are found on multiple levels as they can derive from a patients pre-existing condition or result from the surgical intervention or management of anesthesia. The therapy of hyperkalemia depends on the dimensions of electrolyte disturbance and a distinction can be made between therapeutic measures with a rapid and those with a long-term effect.

[Hemodynamic monitoring in one-lung ventilation]

One-lung ventilation causes adverse effects in pulmonary gas exchange and cardiocirculatory function. These adverse effects become particularly important for patients with underlying cardiopulmonary comorbidities. Alterations in pulmonary gas exchange have been investigated in several experimental and clinical trials. However, the hemodynamic consequences of one-lung ventilation are to a great extent unknown. Furthermore, no conclusive recommendations exist as to which kind of hemodynamic monitoring should be preferred in the situation of one-lung ventilation. Many issues regarding hemodynamic monitoring in one-lung ventilation remain unacknowledged. This article will review the current literature on hemodynamic monitoring in one-lung ventilation in order to derive recommendations for the application of hemodynamic monitoring in this specific peri-operative situation.

Paracrine purinergic signaling determines lung endothelial nitric oxide production

Although the vascular bed is a major source of nitric oxide (NO) production, factors regulating the production remain unclear. We considered the role played by paracrine signaling. Determinations by fluorescence microscopy in isolated, blood-perfused rat and mouse lungs revealed that a brief lung expansion enhanced cytosolic Ca(2+) (Ca(2+)cyt) oscillations in alveolar epithelial (AEC) and endothelial (EC) cells, and NO production in EC. Furthermore, as assessed by a novel microlavage assay, alveolar ATP production increased. Intra-alveolar microinfusion of the purinergic receptor antagonist, PPADS, and the nucleotide hydrolyzing enzyme, apyrase, each completely blocked the Ca(2+)cyt and NO responses in EC. Lung expansion induced Ca(2+)cyt oscillations in mice lacking the P2Y1, but not the P2Y2, purinergic receptors, which were located in the perivascular interstitium basolateral to AEC. Prolonged lung expansion instituted by mechanical ventilation at high tidal volume increased EC expression of nitrotyrosine, indicating development of nitrosative stress in lung microvessels. These findings reveal a novel mechanism in which mechanically induced purinergic signaling couples cross-compartmental Ca(2+)cyt oscillations to microvascular NO production.

Red blood cells induce hypoxic lung inflammation

Hypoxia, which commonly associates with respiratory and cardiovascular diseases, provokes an acute inflammatory response. However, underlying mechanisms are not well understood. Here we report that red blood cells (RBCs) induce hypoxic inflammation by producing reactive oxygen species (ROS) that diffuse to endothelial cells of adjoining blood vessels. Real-time fluorescence imaging of rat and mouse lungs revealed that in the presence of RBC-containing vascular perfusion, hypoxia increased microvascular ROS, and cytosolic Ca(2+), leading to P-selectin-dependent leukocyte recruitment. However, in the presence of RBC-free perfusion, all hypoxia-induced responses were completely inhibited. Because hemoglobin (Hb) autoxidation causes RBC superoxide formation that readily dismutates to H(2)O(2), hypoxia-induced responses were lost when we inhibited Hb autoxidation with CO or nitrite, or when the H(2)O(2) inhibitor, catalase was added to the infusion to neutralize the RBC-derived ROS. By contrast, perfusion with RBCs from BERK-trait mice that are more susceptible to Hb autoxidation and to hypoxia-induced superoxide production enhanced the hypoxia-induced responses. We conclude that in hypoxia, increased Hb autoxidation augments superoxide production in RBCs. Consequently, RBCs release H(2)O(2) that diffuses to the lung microvascular endothelium, thereby initiating Ca(2+)-dependent leukocyte recruitment. These findings are the first evidence that RBCs contribute to hypoxia-induced inflammation.

Role of P-Selectin in Platelet Sequestration in Pulmonary Capillaries during Endotoxemia

BACKGROUND

There is growing evidence that platelets accumulate in the lung and contribute to the pathogenesis of acute lung injury during endotoxemia. The aims of the present study were to localize platelet sequestration in the pulmonary microcirculation and to investigate the role of P-selectin as a molecular mechanism of platelet endothelial cell interaction.

METHODS

We used in vivo fluorescence microscopy to quantify the kinetics of fluorescently labeled erythrocytes and platelets in alveolar capillary networks in rabbit lungs.

RESULTS

Six hours after onset of endotoxin infusion we observed a massive rolling along and firm adherence of platelets to lung capillary endothelial cells whereas under control conditions no platelet sequestration was detected. P-selectin was expressed on the surface of separated platelets which were incubated with endotoxin and in lung tissue. Pretreatment of platelets with fucoidin, a P-selectin antagonist, significantly attenuated the endotoxin-induced platelet rolling and adherence. In contrast, intravenous infusion of fucoidin in endotoxin-treated rabbits did not inhibit platelet sequestration in pulmonary capillaries.

CONCLUSION

We conclude that platelets accumulate in alveolar capillaries following endotoxemia. P-selectin expressed on the surface of platelets seems to play an important role in mediating this platelet-endothelial cell interaction.

Platelet-endothelial cell interaction in pulmonary micro-circulation: the role of PARS

Accumulation of platelets might contribute to acute lung injury during systemic inflammation. The aim of the study was to elucidate the role of the poly (ADP-ribose) synthetase, a nucleotide-polymerizising enzyme, in mediation of platelet-endothelial cell interaction through regulation of adhesion molecules within the pulmonary microcirculation during endotoxemia. We used in vivo fluorescence microscopy to quantify kinetics of fluorescently labeled erythrocytes and platelets in rabbit pulmonary arterioles and venules. Six hours after onset of endotoxin infusion we observed a massive interaction of platelets with the microvascular endothelial cells, whereas under control conditions, no platelet sequestration was measured. An up-regulation of P- and E-selectin was detected in lung tissue following endotoxin infusion by immunohistochemistry and Western blot analysis. Blockade of endothelial P-selectin with fucoidin resulted in a reduction of the endotoxin-induced platelet-endothelial cell interaction. Inhibition of poly (ADP-ribose) synthetase by 3-aminobenzamide inhibited the endotoxin-induced expression of endothelial P- and E-selectin and the subsequent recruitment of platelets. In summary, we provide first in vivo evidence that platelets accumulate in pulmonary microcirculation following endotoxemia. Poly (ADP-ribose) synthetase seems to mediate this platelet-endothelial cell interaction via P- and E-selectin expressed on the surface of microvascular endothelium.

Dynamic intravital fluorescence microscopy--a novel method for the assessment of microvascular permeability in acute pancreatitis

Edema formation is the first manifestation of acute pancreatitis. Microcirculatory derangements like leukocyte-endothelial cell interaction and perfusion failure result in enhancement of microvascular permeability to large molecules playing a pivotal role in the progression of the acutely altered pancreatic tissue. Due to the lack of suitable methods the crucial mechanisms of enhanced permeability in vivo are not very well investigated. Sprague-Dawley rats were randomly assigned to three groups: (a) sham operated animals with normal pancreas, (b) the pancreatitis group induced by 60 min temporary occlusion of the arterial supply followed by reperfusion and (c) the histamine group in which the pancreas was superfused with 10(-5)M histamine. The pharmacokinetics of tetramethylrhodamine-labelled BSA in the intravital microscopic images of a capillary network of the pancreas were densitometrically quantified over 20 min. From these data the effective microvascular permeability was calculated taking also into account morphology of microvessels, elimination rate of the tracer from the intravascular space and capillary microhematocrit. In addition macromolecular leakage of gold-labelled BSA was investigated by electron microscopy. Microvascular permeability was 0.10 +/- 0.02 x 10(-7) cm/s, 0.49 +/- 0.04 x 10(-7) cm/s and 1.21 +/- 0.29 x 10(-7) cm/s for control, ischemia and histamine group, respectively (P < 0.05 ischemia, histamine vs. control and ischemia vs. histamine). Electron microscopy revealed albumin extravasation in the last two groups. We established a technique allowing to quantify microvascular permeability in pancreatic tissue by dynamic intravital microscopy being independent of the investigator. This technique enabling accurate pathophysiologic characterisation in terms of edema formation can form the basis for evaluating in the future novel treatment strategies directed against acute pancreatitis.

Colloidal gold particles as a new in vivo marker of early acute lung injury

Permeability of the endothelial barrier to large molecules plays a pivotal role in the manifestation of early acute lung injury. We present a novel and sensitive technique that brings microanatomical visualization and quantification of microvascular permeability in line. White New Zealand rabbits were anesthetized and ventilated mechanically. Rabbit serum albumin (RSA) was labeled with colloidal gold particles. We quantified macromolecular leakage of gold-labeled RSA and thickening of the gas exchange distance by electron microscopy, taking into account morphology of microvessels. The control group receiving a saline solution represented a normal gas exchange barrier without extravasation of gold-labeled albumin. Infusion of lipopolysaccharide (LPS) resulted in a significant displacement of gold-labeled albumin into pulmonary cells, the lung interstitium, and even the alveolar space. Correspondingly, intravital fluorescence microscopy and digital image analysis indicated thickening of width of alveolar septa. The findings were accompanied by a deterioration of alveolo-arterial oxygen difference, whereas wet/dry ratio and albumin concentration in the bronchoalveolar lavage fluid failed to detect that early stage of pulmonary edema. Inhibition of the nuclear enzyme poly(ADP-ribose) synthetase by 3-aminobenzamide prevented LPS-induced microvascular injury. To summarize: colloidal gold particles visualized by standard electron microscopy are a new and very sensitive in vivo marker of microvascular permeability in early acute lung injury. This technique enabling detailed microanatomical and quantitative pathophysiological characterization of edema formation can form the basis for evaluating novel treatment strategies against acute lung injury.

Role of PARP on iNOS pathway during endotoxin-induced acute lung injury

OBJECTIVE

Excessive nitric oxide (NO) and especially peroxynitrite may cause pulmonary tissue damage, e.g., through lipid peroxidation and/or exhaustion of cellular energy depletion induced by activation of poly (ADP-ribose) polymerase (PARP). Furthermore, PARP seems to aggravate tissue destruction by regulating the expression of respective genes.

DESIGN

Prospective animal study.

SETTING

University research laboratory.

INTERVENTION

We investigated the effect of competitive PARP inhibition by 3-aminobenzamide (3-AB) on the pulmonary iNOS pathway after infusion of lipopolysaccharide (LPS).

MEASUREMENTS AND RESULTS

The pretreatment of rabbits with 3-AB attenuated the LPS-induced iNOS mRNA and protein expression analyzed by RT-PCR and Western blot, and plasma nitrite concentrations quantified by Griess reaction (71+/-6%, 93+/-6% vs baseline). Electromobility shift assay showed an enhanced NF-kappaB and attenuated AP-1 activation after 3-AB vs LPS alone. Lipid peroxidation determined as levels of thiobarbituric acid reactive substances in plasma and lung tissue was reduced by 50% in the LPS+3-AB in comparison to LPS alone. Simultaneously, 3-AB was able to inhibit correspondingly the LPS-induced extravasation of gold-labeled albumin and increase of alveolo-arterial oxygen difference.

CONCLUSION

PARP regulates the pulmonary NO pathway during endotoxemia via AP-1 and not NF-kappaB. Thus, pharmacological inhibition of PARP might be an effective intervention to prevent endotoxin-induced lung injury, interrupting the vicious circle of NO production and PARP activation.

Role of poly(ADP-ribose) synthetase in pulmonary leukocyte recruitment

During systemic inflammation, recruitment and activation of leukocytes in the pulmonary microcirculation may result in a potentially life-threatening acute lung injury. We elucidated the role of the poly(ADP-ribose) synthetase (PARS), a nucleotide-polymerizing enzyme, in the regulation of leukocyte recruitment within the lung with regard to the localization in the pulmonary microcirculation and in correlation to hemodynamics in the respective vascular segments and expression of intercellular adhesion molecule 1 during endotoxemia. Inhibition of PARS by 3-aminobenzamide reduced the endotoxin-induced leukocyte recruitment within pulmonary arterioles, capillaries, and venules in rabbits as quantified by in vivo fluorescence microscopy. Microhemodynamics and thus shear rates in all pulmonary microvascular segments remained constant. Simultaneously, inhibition of PARS with 3-aminobenzamide suppressed the endotoxin-induced adhesion molecules expression as demonstrated for intercellular adhesion molecule 1 by immunohistochemistry and Western blot analysis. We confirmed this result with the use of PARS knockout mice. The inhibitory effect of 3-aminobenzamide on leukocyte recruitment was associated with a reduction of pulmonary capillary leakage and edema formation. We first provide evidence that PARS activation mediates the leukocyte sequestration in pulmonary microvessels through upregulation of adhesion molecules. As reactive oxygen species released from leukocyte are supposed to cause an upregulation of adhesion molecules we conclude that PARS inhibition contributes to termination of this vicious cycle and inhibits the inflammatory process.

Dual role of inducible nitric oxide synthase in acute asbestos-induced lung injury

Reactive oxygen and nitrogen species have been implicated in the pathogenesis of asbestos fibers-associated pulmonary diseases. By comparing the responses of inducible nitric oxide synthase (iNOS) knockout and wild-type mice we investigated the consequences of iNOS expression for the development of the inflammatory response and tissue injury upon intratracheal instillation of asbestos fibers. Exposure to asbestos fibers resulted in an increased iNOS mRNA and protein expression in the lungs from wild-type mice. Moreover, iNOS knockout mice exhibited an exceeded pulmonary expression and production of TNF-alpha as well as a higher influx of neutrophils into the alveolar space than wild-type mice. In contrast, iNOS knockout animals displayed an attenuated oxidant-related tissue injury reflected in a decrease in protein leakage and LDH release into the alveolar space as well as weaker nitrotyrosine staining of lung tissue compared to wild-type mice. Data presented here indicate that iNOS-derived NO exerts a dichotomous role in acute asbestos-induced lung injury in that iNOS deficiency resulted in an exacerbated inflammatory response but improved oxidant-promoted lung tissue damage.

Early inflammatory response to asbestos exposure in rat and hamster lungs: role of inducible nitric oxide synthase

Recent studies have suggested that inducible nitric oxide synthase (iNOS) plays a role in the development of asbestos-related pulmonary disorders. The pulmonary reactions of rats and hamsters upon exposure to asbestos fibers are well known to be disparate. In addition, in vitro experiments have indicated that mononuclear phagocytes from hamsters, in contrast to those from rats, lack the iNOS pathway. Therefore, the purpose of this study was to investigate whether rats and hamsters differ in lung iNOS expression in vivo upon exposure to asbestos fibers and whether differences in iNOS induction are associated with differences in the acute pulmonary inflammatory reaction. Body weight, alveolar-arterial oxygen difference, differential cell count in bronchoalveolar lavage fluid, total protein leakage, lung myeloperoxidase activity and lipidperoxidation, wet/dry ratio, iNOS mRNA and protein expression, and nitrotyrosine staining of lung tissue were determined 1 and 7 days after intratracheal instillation of asbestos fibers in CD rats and Syrian golden hamsters. Exposure of rats to asbestos fibers resulted in enhanced pulmonary iNOS expression and nitrotyrosine staining together with an acute inflammation that was characterized by an influx of neutrophils, enhanced myeloperoxidase activity and lipid peroxidation, damage of the alveolar-capillary membrane, edema formation, and impairment of gas exchange. In comparison, instillation of asbestos fibers in hamsters resulted in a significantly milder inflammatory reaction of the lung with no induction of iNOS in pulmonary cells. The data obtained provide important information to understand the underlying mechanisms of species differences in the pulmonary response upon exposure to asbestos fibers.

Leukocyte sequestration in pulmonary microvessels and lung injury following systemic complement activation in rabbits

Inflammatory reactions are associated with sequestration of leukocytes in the lung. Complement activation leads to accumulation of leukocytes in alveolar septa and alveoli, to lung edema and hemorrhage. Although in organs other than the lung leukocytes interact with the vascular endothelium only in postcapillary venules, alveolar capillaries are considered to be the site of leukocyte sequestration in the lung. However, pulmonary venules and arterioles have not been investigated systematically after complement activation so far. A closed thoracic window was implanted in anesthetized rabbits; leukocytes and red blood cells were stained, and the movement of these cells was measured in superficial pulmonary arterioles, venules and alveolar capillaries using fluorescence video microscopy before and 30 and 60 min after infusion of cobra venom factor (CVF). Erythrocyte velocity and macrohemodynamic conditions did not change after CVF infusion and were not different from the sham-treated controls. The number of sticking leukocytes increased significantly compared to baseline and control: by 150% in arterioles and in venules and by 740% in alveolar capillaries within 60 min after CVF infusion. The width of alveolar septa in vivo was significantly enlarged after CVF infusion, indicating interstitial pulmonary edema. At the end of the experiments, myeloperoxidase activity was higher in the CVF group, showing leukocyte sequestration in the whole organ. It is concluded that complement activation by CVF induces leukocyte sequestration in lung arterioles, venules and alveolar capillaries and leads to mild lung injury.

Intraoperative detection of malignant gliomas by 5-aminolevulinic acid-induced porphyrin fluorescence

OBJECTIVE

Survival after surgery and radiotherapy for the treatment of malignant gliomas is linked to the completeness of tumor removal. Therefore, methods that permit intraoperative identification of residual tumor tissue may be of benefit. In a preliminary investigation, we have studied the value of fluorescent porphyrins that accumulate in malignant tissue after administration of a precursor (5-aminolevulinic acid) for labeling of malignant gliomas in nine patients.

METHODS

Three hours before the induction of anesthesia, 10 mg 5-aminolevulinic acid/kg body weight was administered orally. Intraoperatively, red porphyrin fluorescence was observed with a 455-nm long-pass filter after excitation with violet-blue (375-440 nm) xenon light and was verified by analysis of fluorescence spectra. Fluorescing and nonfluorescing samples taken from the tumor perimeters were examined histologically or used to study the photobleaching of porphyrins by excitation light and white light from the operating microscope. Plasma and erythrocyte porphyrin levels were determined by fluorescence photometry.

RESULTS

Normal brain tissue revealed no porphyrin fluorescence, whereas tumor tissue was distinguished by bright red fluorescence. For a total of 89 tissue biopsies, sensitivity was 85% and specificity was 100% for the detection of malignant tissue. For seven of nine patients, visible porphyrin fluorescence led to further resection of the tumor. Under operating light conditions, fluorescence decayed to 36% in 25 minutes for violet-blue light and in 87 minutes for white light. Plasma and erythrocyte porphyrin contents increased slightly, without exceeding normal levels.

CONCLUSION

Our observations suggest that 5-aminolevulinic acid-induced porphyrin fluorescence may label malignant gliomas safely and accurately enough to enhance the completeness of tumor removal.

Excessive arterial thrombus in spherocytosis. A case report

Spherocytosis is the most common of the hereditary hemolytic anemias, with characteristically shaped erythrocytes. An unusually large amount of arterial thrombus was documented in a dissected artery after angioplasty in a patient with spherocytosis. It is hypothesized that the excessive arterial thrombus may have been linked to the spherocytosis.