Antagonists of the Vasopressin V1 Receptor and of the β1-Adrenoceptor Inhibit Cytotoxic Brain Edema in Stroke by Effects on Astrocytes – but the Mechanisms Differ

Brain edema is a serious complication in ischemic stroke because even relatively small changes in brain volume can compromise cerebral blood flow or result in compression of vital brain structures on account of the fixed volume of the rigid skull. Literature data indicate that administration of either antagonists of the V1 vasopressin (AVP) receptor or the β₁-adrenergic receptor are able to reduce edema or infarct size when administered after the onset of ischemia, a key advantage for possible clinical use. The present review discusses possible mechanisms, focusing on the role of NKCC1, an astrocytic cotransporter of Na⁺, K⁺, 2Cl^- and water and its activation by highly increased extracellular K⁺ concentrations in the development of cytotoxic cell swelling. However, it also mentions that due to a 3/2 ratio between Na⁺ release and K⁺ uptake by the Na⁺,K⁺-ATPase driving NKCC1 brain extracellular fluid can become hypertonic, which may facilitate water entry across the blood-brain barrier, essential for development of edema. It shows that brain edema does not develop until during reperfusion, which can be explained by lack of metabolic energy during ischemia. V1 antagonists are likely to protect against cytotoxic edema formation by inhibiting AVP enhancement of NKCC1-mediated uptake of ions and water, whereas β₁-adrenergic antagonists prevent edema formation because β₁-adrenergic stimulation alone is responsible for stimulation of the Na⁺,K⁺-ATPase driving NKCC1, first and foremost due to decrease in extracellular Ca²⁺ concentration. Inhibition of NKCC1 also has adverse effects, e.g. on memory and the treatment should probably be of shortest possible duration.     

Can New Inflammatory Markers Improve the Diagnosis of Acute Appendicitis?

Background

The diagnosis of appendicitis is difficult and resource consuming. New inflammatory markers have been proposed for the diagnosis of appendicitis, but their utility in combination with traditional diagnostic variables has not been tested. Our objective is to explore the potential of new inflammatory markers for improving the diagnosis of appendicitis.

Methods

The diagnostic properties of the six most promising out of 21 new inflammatory markers (interleukin [IL]-6, chemokine ligand [CXCL]-8, chemokine C–C motif ligand [CCL]-2, serum amyloid A [SAA], matrix metalloproteinase [MMP]-9, and myeloperoxidase [MPO]) were compared with traditional diagnostic variables included in the Appendicitis Inflammatory Response (AIR) score (right iliac fossa pain, vomiting, rebound tenderness, guarding, white blood cell [WBC] count, proportion neutrophils, C-reactive protein and body temperature) in 432 patients with suspected appendicitis by uni- and multivariable regression models.

Results

Of the new inflammatory variables, SAA, MPO, and MMP9 were the strongest discriminators for all appendicitis (receiver operating characteristics [ROC] 0.71) and SAA was the strongest discriminator for advanced appendicitis (ROC 0.80) compared with defence or rebound tenderness, which were the strongest traditional discriminators for all appendicitis (ROC 0.84) and the WBC count for advanced appendicitis (ROC 0.89). CCL2 was the strongest independent discriminator beside the AIR score variables in a multivariable model. The AIR score had an ROC area of 0.91 and could correctly classify 58.3 % of the patients, with an accuracy of 92.9 %. This was not improved by inclusion of the new inflammatory markers.

Conclusion

The conventional diagnostic variables for appendicitis, as combined in the AIR score, is an efficient screening instrument for classifying patients as low-, indeterminate-, or high-risk for appendicitis. The addition of the new inflammatory variables did not improve diagnostic performance further.     

Charlson score as a single pertinent criterion to select candidates for active surveillance among patients with small renal masses

Purpose

The aim of the study was to assess the outcome after nephron-sparing surgery (NSS) of patients with small renal masses (SRMs) who would have been eligible for active surveillance (AS).

Methods

Data were collected retrospectively for 758 patients who underwent NSS over a 5-year period. Outcomes were assessed in two groups of patients who were eligible for AS according to different criteria. Group 1 criteria were as follows: age >75 years, renal mass ≤4 cm, significant comorbidities [Charlson Comorbidity Index (CCI) >2]. Group 2 criteria were as follows: any SRM ≤ 4 cm regardless of age, severe comorbidities with a 10-year mortality risk >50 % (CCI > 4). The two groups were not compared statistically because some patients were included in both.

Results

Fifty-five patients (7.3 %) were included in Group 1 and 62 (8.2 %) in Group 2. There was a significant proportion of benign tumours in Group 1 (N = 6; 11 %) and Group 2 (N = 6; 10 %). Six (11 %) positive margins were observed in Group 1 and 8 (13 %) in Group 2. The 2- and 5-year recurrence-free survival rates were 100 and 77.4 %, respectively, in Group 1, and 88.5 and 79.6 % in Group 2. The 2- and 5-year overall survival rates were 100 and 74.7 % in Group 1, and 96.7 and 78.1 % in Group 2.

Conclusions

The majority of patients with SRMs who would have been eligible for AS had no recurrence after initial tumour removal. In these patients, a CCI > 4 appeared to be a pertinent criterion to identify those patients less likely to benefit from immediate surgery.     

Supporting older patients in working on rehabilitation goals: A scoping review of nursing interventions

Background

Nurses are consistently present throughout the rehabilitation of older patients but are apprehensive about performing goal-centred care in the multidisciplinary team.

Objectives

The aim of this review was to explore working interventions on setting goals and working with goals designed for nurses in geriatric rehabilitation, and to describe their distinctive features.

Methods

We performed a scoping review. We searched MEDLINE and CINAHL through August 4, 2021. Search terms related to the following themes: nurses, rehabilitation, geriatric, goal and method. We used snowballing to find additional. From the selected studies, we systematically extracted data on means, materials and the nursing role and summarized them in a narrative synthesis, using intervention component analysis.

Results

The study includes 13 articles, describing 11 interventions which were developed for six different aims: improving multidisciplinary team care; increasing patient centredness; improving disease management by patients; improving the psychological, and emotional rehabilitation; increasing the nursing involvement in rehabilitation; or helping patients to achieve goals. The interventions appeal to four aspects of the nursing profession: assessing self-care skills incorporating patient's preferences; setting goals with patients, taking into account personal needs and what is medically advisable; linking the needs of the patient with multidisciplinary professional treatment and vice versa; and thus, playing an intermediate role and supporting goal achievement.

Conclusions

The interventions show that in goal-centred care, the nurse might play an important unifying role between patients and the multidisciplinary team. With the support of nurses, the patient may become more aware of the rehabilitation process and transfer of ownership of treatment goals from the multidisciplinary team to the patient might be achieved. Not many interventions were found meant to support the nursing role. This may indicate a blind spot in the rehabilitation community to the additional value of its contribution.     

7 tesla magnetic resonance imaging: A closer look at substantia nigra anatomy in Parkinson's disease

A hallmark of Parkinson's disease (PD) is the progressive neurodegeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). Dopaminergic denervation is commonly imaged using radiotracer imaging in target structures such as the striatum. Until recently, imaging made only a modest contribution to detecting neurodegenerative changes in the substantia nigra (SN) directly. Histologically, the SN is subdivided into the ventral pars reticulata and the dorsal pars compacta, which is composed of dopaminergic neurons. In humans, dopaminergic neurons, which are known to accumulate neuromelanin, form clusters of cells (nigrosomes) that penetrate deep into the SN pars reticulata (SNr). The SNr contains higher levels of iron than the SNc in normal subjects. Neuromelanin and T2*‐weighted imaging therefore better detect the SNc and the SNr, respectively. The development of ultra‐high field 7 Tesla (7T) magnetic resonance imaging (MRI) provided the increase in spatial resolution and in contrast that was needed to detect changes in SN morphology. 7T MRI allows visualization of nigrosome‐1 as a hyperintense signal area on T2*‐weighted images in the SNc of healthy subjects and its absence in PD patients, probably because of the loss of melanized neurons and the increase of iron deposition. This review is designed to provide a better understanding of the correspondence between the outlines and subdivisions of the SN detected using different MRI contrasts and the histological organization of the SN. The recent findings obtained at 7T will then be presented in relation to histological knowledge. © 2014 International Parkinson and Movement Disorder Society     

Epac-Rap Signaling Reduces Oxidative Stress in the Tubular Epithelium

Activation of Rap1 by exchange protein activated by cAMP (Epac) promotes cell adhesion and actin cytoskeletal polarization. Pharmacologic activation of Epac-Rap signaling by the Epac-selective cAMP analog 8-pCPT-2′-O-Me-cAMP during ischemia-reperfusion (IR) injury reduces renal failure and application of 8-pCPT-2′-O-Me-cAMP promotes renal cell survival during exposure to the nephrotoxicant cisplatin. Here, we found that activation of Epac by 8-pCPT-2′-O-Me-cAMP reduced production of reactive oxygen species during reoxygenation after hypoxia by decreasing mitochondrial superoxide production. Epac activation prevented disruption of tubular morphology during diethyl maleate–induced oxidative stress in an organotypic three-dimensional culture assay. In vivo renal targeting of 8-pCPT-2′-O-Me-cAMP to proximal tubules using a kidney-selective drug carrier approach resulted in prolonged activation of Rap1 compared with nonconjugated 8-pCPT-2′-O-Me-cAMP. Activation of Epac reduced antioxidant signaling during IR injury and prevented tubular epithelial injury, apoptosis, and renal failure. Our data suggest that Epac1 decreases reactive oxygen species production by preventing mitochondrial superoxide formation during IR injury, thus limiting the degree of oxidative stress. These findings indicate a new role for activation of Epac as a therapeutic application in renal injury associated with oxidative stress.Renal ischemia-reperfusion (IR) injury is an important cause of AKI¹ and a significant risk factor for the development of renal dysfunction after kidney transplantation.² During IR injury, morphologic and functional alterations of the proximal tubular epithelium occur that are linked to the development of renal failure and activation of immune cells via release of proinflammatory cytokines.³Exchange protein activated by cAMP (Epac) is a guanine nucleotide exchange factor for the small GTPase Rap1.⁴ Activation of Epac by cAMP or by the Epac-selective cAMP analog 8-pCPT-2′-O-Me-cAMP (also referred to as 007) induces functional activation of Rap1.⁵ Initial studies showed that Epac-Rap signaling enhances cell adhesion by supporting maturation of cell-cell junctions^6,7 and promoting integrin-mediated cell-matrix adhesion.^8,9 In line with these studies, we recently demonstrated that selective activation of Epac reduces proximal tubular epithelial cell (PTEC) detachment during IR injury using in vitro and in vivo models.¹⁰ Activation of Epac-Rap was associated with reduced expression of markers for cellular stress in PTECs. In addition, in vitro cisplatin-induced apoptosis of PTECs could be significantly reduced by activation of Epac and this was also associated with improved adhesion of cells.¹¹ On the basis of these findings, we hypothesized that activation of Epac-Rap signaling may protect against a common cytotoxic event in these injury models.Unbalanced and uncontrolled production of reactive oxygen species (ROS) is an important mediator of cell injury and occurs during cisplatin nephrotoxicity,¹² IR injury,¹³ and renal fibrosis.¹⁴ In renal pathology, intracellular ROS can be produced enzymatically such as by NADPH oxidase (NOX) complexes or derive from dysfunctional mitochondrial activity. Mitochondrial ROS production appears to be the driving force behind hypoxia-reoxygenation cell injury¹⁵ and cisplatin cytotoxicity.¹⁶Here we studied the role of specific proximal tubular activation of Epac and how this protects against renal injury in both in vitro and in vivo models for IR injury. We found that ROS production during reoxygenation after hypoxia was decreased by activation of Epac. Selective proximal tubular activation of Epac by renal targeting of 8-pCPT-2′-O-Me-cAMP conjugated to lysozyme (LZM-007) reduced oxidative stress in an in vivo model for IR injury and significantly decreased IR injury–associated renal failure and tubular damage. Our data show that Epac activation reduces ROS-mediated cellular injury in renal disease and may be a therapeutic strategy for modulation of oxidative stress.