The Superblock model: A review of an innovative urban model for sustainability, liveability, health and well-being.

INTRODUCTION: Current urban and transport planning practices have significant negative health, environmental, social and economic impacts in most cities. New urban development models and policies are needed to reduce these negative impacts. The Superblock model is one such innovative urban model that can significantly reduce these negative impacts through reshaping public spaces into more diverse uses such as increase in green space, infrastructure supporting social contacts and physical activity, and through prioritization of active mobility and public transport, thereby reducing air pollution, noise and urban heat island effects. This paper reviews key aspects of the Superblock model, its implementation and initial evaluations in Barcelona and the potential international uptake of the model in Europe and globally, focusing on environmental, climate, lifestyle, liveability and health aspects. METHODS: We used a narrative meta-review approach and PubMed and Google scholar databases were searched using specific terms. RESULTS: The implementation of the Super block model in Barcelona is slow, but with initial improvement in, for example, environmental, lifestyle, liveability and health indicators, although not so consistently. When applied on a large scale, the implementation of the Superblock model is not only likely to result in better environmental conditions, health and wellbeing, but can also contribute to the fight against the climate crisis. There is a need for further expansion of the program and further evaluation of its impacts and answers to related concerns, such as environmental equity and gentrification, traffic and related environmental exposure displacement. The implementation of the Superblock model gained a growing international reputation and variations of it are being planned or implemented in cities worldwide. Initial modelling exercises showed that it could be implemented in large parts of many cities. CONCLUSION: The Superblock model is an innovative urban model that addresses environmental, climate, liveability and health concerns in cities. Adapted versions of the Barcelona Superblock model are being implemented in cities around Europe and further implementation, monitoring and evaluation are encouraged. The Superblock model can be considered an important public health intervention that will reduce mortality and morbidity and generate cost savings for health and other sectors.

Outcome of endoscopic vacuum therapy for duodenal perforation.

BACKGROUND: Duodenal defects are complex clinical situations, and their management is challenging and associated with high mortality. Besides surgery, endoscopic treatment options exist, but the size and location of the perforation can limit their application. We present a retrospective study, demonstrating a successful application of endoscopic vacuum therapy (EVT) for duodenal leaks. METHODS: We performed a retrospective study of all patients who underwent EVT for duodenal perforations between 2016 and 2021 at two tertiary centers. We analyzed demographic and clinical patient characteristics, surgical outcomes, leak characteristics, sponge-related complications, and success rate. RESULTS: Indications for treatment with EVT in the duodenum consisted of leak after duodenal suture of a perforated ulcer (n = 4), iatrogenic perforation after endoscopic resection (n = 2), iatrogenic perforation during surgery (n = 2), and anastomotic leak after upper gastrointestinal surgery (n = 2). EVT was used as a first-line treatment in seven patients and as a second-line treatment in three patients. EVT was successfully applied in all interventions (n = 10, 100%). Overall, EVT lead to definitive closure of the defects in eight out of ten patients (80%). No severe EVT-related adverse events occurred. CONCLUSION: EVT is safe and technically feasible, so it emerges as a promising endoscopic treatment option for duodenal leaks. However, multidisciplinary collaboration and management are important to reduce the occurrence of postoperative complications, and to improve recovery rates.

Time to endoscopic vacuum therapy-lessons learned after > 150 robotic-assisted minimally invasive esophagectomies (RAMIE) at a German high-volume center.

OBJECTIVE OF THE STUDY: In esophageal surgery, anastomotic leak (AL) remains one of the most severe and critical adverse events after oncological esophagectomy. Endoscopic vacuum therapy (EVT) can be used to treat AL; however, in the current literature, treatment outcomes and reports on how to use this novel technique are scarce. The aim of this study was to evaluate the outcomes of patients with an AL after IL RAMIE and to determine whether using EVT as an treatment option is safe and feasible. MATERIAL AND METHODS: This study includes all patients who developed an Esophagectomy Complications Consensus Group (ECCG) type II AL after IL RAMIE at our center between April 2017 and December 2021. The analysis focuses on time to EVT, duration of EVT, and follow up treatments for these patients. RESULTS: A total of 157 patients underwent an IL RAMIE at our hospital. 21 patients of these (13.4%) developed an ECCG type II AL. One patient died of unrelated Covid-19 pneumonia and was excluded from the study cohort. The mean duration of EVT was 12 days (range 4-28 days), with a mean of two sponge changes (range 0-5 changes). AL was diagnosed at a mean of 8 days post-surgery (range 2-16 days). Closure of the AL with EVT was successful in 15 out of 20 patients (75%). Placement of a SEMS (Self-expandlable metallic stent) after EVT was performed in four patients due to persisting AL. Overall success rate of anastomotic sealing independently of the treatment modality was achieved in 19 out of 20 Patients (95%). No severe EVT-related adverse events occurred. CONCLUSION: This study shows that EVT can be a safe and effective endoscopic treatment option for ECCG type II AL.

Assessment of pyloric sphincter physiology after Ivor-Lewis esophagectomy using an endoluminal functional lumen imaging probe.

OBJECTIVE OF THE STUDY: The most common functional complication after Ivor-Lewis esophagectomy is the delayed emptying of the gastric conduit (DGCE) for which several diagnostic tools are available, e.g. chest X-ray, upper esophagogastroduodenoscopy (EGD) and water-soluble contrast radiogram. However, none of these diagnostic tools evaluate the pylorus itself. Our study demonstrates the successful measurement of pyloric distensibility in patients with DGCE after esophagectomy and in those without it. METHODS AND PROCEDURES: Between May 2021 and October 2021, we performed a retrospective single-centre study of all patients who had an oncological Ivor-Lewis esophagectomy and underwent our post-surgery follow-up programme with surveillance endoscopies and computed tomography scans. EndoFlip™ was used to perform measurements of the pylorus under endoscopic control, and distensibility was measured at 40 ml, 45 ml and 50 ml balloon filling. RESULTS: We included 70 patients, and EndoFlip™ measurement was feasible in all patients. Successful application of EndoFlip™ was achieved in all interventions (n = 70, 100%). 51 patients showed a normal postoperative course, whereas 19 patients suffered from DGCE. Distensibility proved to be smaller in patients with symptoms of DGCE compared to asymptomatic patients. For 40 ml, 45 ml and 50 ml, the mean distensibility was 6.4 vs 10.1, 5.7 vs 7.9 and 4.5 vs 6.3 mm2/mmHg. The differences were significant for all three balloon fillings. No severe EndoFlip™ treatment-related adverse events occurred. CONCLUSION: Measurement with EndoFlip™ is a safe and technically feasible endoscopic option for measuring the distensibility of the pylorus. Our study shows that the distensibility in asymptomatic patients after esophagectomy is significantly higher than that in patients suffering from DGCE. However, more studies need to be conducted to demonstrate the general use of EndoFlip™ measurement of the pylorus after esophagectomy.

A convolutional neural network for bleeding detection in capsule endoscopy using real clinical data.

BACKGROUND: The goal of the present study was to develop a convolutional neural network for the detection of bleedings in capsule endoscopy videos using realistic clinical data from one single-centre. METHODS: Capsule endoscopy videos from all 133 patients (79 male, 54 female; meanage = 53.73 years, SDage = 26.13) who underwent capsule endoscopy at our institution between January 2014 and August 2018 were screened for pathology. All videos were screened for pathology by two independent capsule experts and confirmed findings were checked again by a third capsule expert. From these videos, 125 pathological findings (individual episodes of bleeding spanning a total of 5696 images) and 103 non-pathological findings (sections of normal mucosal tissue without pathologies spanning a total of 7420 images) were used to develop and validate a neural network (Inception V3) using transfer learning. RESULTS: The overall accuracy of the model for the detection of bleedings was 90.6% [95%CI: 89.4%-91.7%], with a sensitivity of 89.4% [95%CI: 87.6%-91.2%] and a specificity of 91.7% [95%CI: 90.1%-93.2%]. CONCLUSION: Our results show that neural networks can detect bleedings in capsule endoscopy videos under realistic, clinical conditions with an accuracy of 90.6%, potentially reducing reading time per capsule and helping to improve diagnostic accuracy.

A new hybrid stent using endoscopic vacuum therapy in treating esophageal leaks: a prospective single-center experience of its safety and feasibility with mid-term follow-up.

Self-expandable metal stents (SEMS) and endoscopic vacuum therapy (EVT) are endoscopic options for treating leaks of the esophagus. VACStent® is a variant of SEMS that aims to combine the advantages of SEMS and EVT in one device. Due to this unique construction, VACStent® can build a barrier to the leak and facilitate wound healing with EVT, all while maintaining intestinal passage. We present the first prospective feasibility study of VACStent® for treating leaks of the upper gastrointestinal tract. Between September 2019 and November 2020, we performed a prospective, investigator-initiated, single-center study and included all patients who underwent endoscopic stenting with VACStent® for various kinds of esophageal leaks, such as spontaneous, iatrogenic or anastomotic leaks. We included 20 patients, who underwent a total of 24 endoscopic VACStent® implantations. Technical success of the application of the VACStent® was achieved in all interventions (n = 24, 100%). Overall, clinical success in closing the leaks with VACStent® treatment was achieved in 60% of patients (12/20). No severe VACStent® treatment-related adverse events occurred. Oral feeding with supplement high-energy drinks failed in all patients due to clogging of the suction tube. VACStent® is a safe and feasible endoscopic treatment option for leaks of the upper gastrointestinal tract. However, our data could not show the expected advantage of orally feeding the patients during the treatment with the VACStent® in its current form. Efficacy of VACStent® compared to EVT or SEMS needs to be investigated in a further study. ClinicalTrials.gov Identifier: NCT03962179.

Outcome of prophylactic endoscopic vacuum therapy for high-risk anastomosis after esophagectomy.

Background: Endoscopic vacuum therapy (EVT) has become an established procedure for the treatment of anastomotic leaks (AL) in upper gastrointestinal surgery. A novel approach is the use of EVT for preventing leaks in high-risk anastomosis. The aim of this study was to analyze the outcome of prophylactic EVT (pEVT) in patients receiving surgical revision of the anastomosis after oncological Ivor-Lewis esophagectomy (ILE) due to AL.Material and methods: Between June 2016 and February 2019, all patients who underwent anastomotic revision after ILE due to a confirmed AL were included. The primary outcome was the success rate of pEVT, which was defined as absence of an AL after revision. Secondary outcome parameters were duration of treatment, inflammatory levels, and ICU/hospital stay.Results: Twenty-one patients underwent anastomotic revision due to an AL. The cause of the AL was ischemia in nine patients (42.9%) and non-ischemia (other) in 12 patients (57.1%). PEVT was performed in 14 patients (66.6%). The overall success rate of pEVT was five out of 14 patients (35.7%).Conclusions: Prophylactic EVT cannot prevent a re-leak in patients with high-risk anastomosis due to surgical revision of an AL after oncological ILE. However, pEVT might help to control the clinical condition of these patients.

[GERD and Barett: Natural Course of One Disease - Update Diagnostics and Therapy]. / GERD und Barrett.

GERD and Barett: Natural Course of One Disease - Update Diagnostics and Therapy Abstract. The gastroesophageal reflux disease (GERD) represents a relatively frequent condition, which clinically includes orocervical, thoracic and abdominal complaints. GERD is defined as pathological gastroesophageal acidic reflux, which consecutively leads to mucosal damage of the esophagus such as reflux esophagitis. The most common symptom of GERD is heartburn but GERD symptoms include various complaints, which need to be considered in diagnosis and therapy. Besides endoscopy, barium swallow, pH metry and manometry are counted among the routine diagnostics for GERD patients. For therapy, dietary and lifestyle measures come along with medication such as proton pump inhibitors (PPI) as daily medication and antacids on demand. It has been demonstrated that anti-reflux surgery, minimally invasive fundoplication or magnet augmentation of the lower esophageal sphincter, produces an equal and lasting effect on GERD compared to PPI. Surgery is preferred in case of large hiatal hernia of voluminous reflux. Success of therapy is given if esophageal exposure to acid is reduced, which shows in remission of esophagitis or which can be demonstrated through pH-metry control. Additionally, improvement of quality of life stands in the focus of GERD treatment, which is to be considered for every therapeutic step. Barrett esophagus represents a subtype of GERD with rising incidence in Western countries. As potential precancerous lesion, the Barrett's esophagus is to be diagnosed early and needs to undergo a risk stratified surveillance in order to prevent dysplasia or carcinoma. Patients with low grade dysplasia, high grade dysplasia or early Barrett's carcinoma should be treated endoscopically. Soon artificial intelligence might contribute to improvement of Barrett's esophagus surveillance and treatment.

The apelin receptor influences biomechanical and morphological properties of endothelial cells.

The adaption of endothelial cells to local flow conditions is a multifunctional process which leads to distinct alterations in cell shape, the subcellular distribution of structural proteins, and cellular function. G-protein-coupled receptors (GPCRs) have been identified to be fundamentally involved in such processes. Recently, we and others have shown that the expression of the endothelial GPCR apelin receptor (APJ) is regulated by fluid flow and that activation of APJ participates in signaling pathways which are related to processes of mechanotransduction. The present study aims to illuminate these findings by further visualization of APJ function. We show that APJ is located to the cellular junctions and might thus be associated with platelet endothelial cell adhesion molecule-1 (PECAM-1) in human umbilical vein endothelial cells (HUVEC). Furthermore, siRNA-mediated silencing of APJ expression influences the shear-induced adaption of HUVEC in terms of cytoskeletal remodeling, cellular elasticity, cellular motility, attachment, and distribution of adhesion complexes. Taken together, our results demonstrate that APJ is crucial for complemented endothelial adaption to local flow conditions.

Megakaryocytes and platelets express nicotinic acetylcholine receptors but nicotine does not affect megakaryopoiesis or platelet function.

In our previous investigations we have shown that platelets and their precursors express nicotinic α7 acetylcholine receptors (nAChRα7) that are involved in platelet function and in vitro differentiation of the megakaryoblastic cell line MEG-01. In this study, we were interested in the expression analysis of additional nAChR and the effects of nicotine in an ex vivo model using megakaryocytic cells differentiated from cord blood derived CD34(+) cells (CBMK) and an in vivo model using blood samples from smokers. CBMK were differentiated with thrombopoietin (TPO) for up to 17 days. Quantitative real-time PCR (QRT-PCR), Western blot analysis and flow cytometry were used to investigate nAChR expression (nAChRα7, nAChRα4, nAChRß2) and nicotine effects. In blood samples of 15 nonsmokers and 16 smokers platelet parameters (count, mean platelet volume--MPV and platelet distribution width--PDW) were determined as indicators for changes of in vivo megakaryopoiesis. Platelet function was determined by the use of whole blood aggregometry and flow cytometry. The functional role of nAChR was evaluated using specific antagonists in aggregometry. CHRNA7, CHRNA4 and CHRNB2 gene transcripts and the corresponding proteins could be identified in CBMK during all stages of differentiation. Platelets contain nAChRα7 and nAChRß2 but not nAChRα4. Nicotine had no effect on TPO-induced differentiation of CBMK. There was no significant difference in all platelet parameters of the smokers compared to the nonsmokers. In line with this, cholinergic gene transcripts as well as the encoded proteins were equally expressed in both the study groups. Despite our observation of nAChR expression in megakaryopoiesis and platelets, we were not able to detect effects of nicotine in our ex vivo and in vivo models. Thus, the functional role of the nAChR in these cells remains open.

Using an Endoluminal Functional Lumen Imaging Probe (EndoFLIP™) to Compare Pyloric Function in Patients with Gastroparesis to Patients After Esophagectomy.

BACKGROUND: Gastroparesis (GP) occurs in patients after upper gastrointestinal surgery, in patients with diabetes or systemic sclerosis and in idiopathic GP patients. As pyloric dysfunction is considered one of the underlying mechanisms, measuring this mechanism with EndoFLIP™ can lead to a better understanding of the disease. METHODS: Between November 2021 and March 2022, we performed a retrospective single-centre study of all patients who had non-surgical GP, post-surgical GP and no sign of GP after esophagectomy and who underwent our post-surgery follow-up program with surveillance endoscopies and further exams. EndoFLIP™ was used to perform measurements of the pylorus, and distensibility was measured at 40 ml, 45 ml and 50 ml balloon filling. RESULTS: We included 66 patients, and successful application of the EndoFLIP™ was achieved in all interventions (n = 66, 100%). We identified 18 patients suffering from non-surgical GP, 23 patients suffering from GP after surgery and 25 patients without GP after esophagectomy. At 40, 45 and 50 ml balloon filling, the mean distensibility in gastroparetic patients was 8.2, 6.2 and 4.5 mm2/mmHg; 5.4, 5.1 and 4.7 mm2/mmHg in post-surgical patients suffering of GP; and 8.5, 7.6 and 6.3 mm2/mmHg in asymptomatic post-surgical patients. Differences between symptomatic and asymptomatic patients were significant. CONCLUSION: Measurement with EndoFLIP™ showed that asymptomatic post-surgery patients seem to have a higher pyloric distensibility. Pyloric distensibility and symptoms of GP seem to correspond.

Evaluation of viscosities of typical drainage fluids to promote more evidence-based catheter size selection.

Percutaneous drainage is a first-line therapy for abscesses and other fluid collections. However, experimental data on the viscosity of body fluids are scarce. This study analyses the apparent viscosity of serous, purulent and biliary fluids to provide reference data for the evaluation of drainage catheters. Serous, purulent and biliary fluid samples were collected during routine drainage procedures. In a first setup, the apparent kinematic viscosity of 50 fluid samples was measured using an Ubbelohde viscometer. In a second setup, the apparent dynamic viscosity of 20 fluid samples obtained during CT-guided percutaneous drainage was measured using an in-house designed capillary extrusion experiment. The median apparent kinematic viscosity was 0.96 mm2/s (IQR 0.90-1.15 mm2/s) for serous samples, 0.98 mm2/s (IQR 0.97-0.99 mm2/s) for purulent samples and 2.77 mm2/s (IQR 1.75-3.70 mm2/s) for biliary samples. The median apparent dynamic viscosity was 1.63 mPa*s (IQR 1.27-2.09 mPa*s) for serous samples, 2.45 mPa*s (IQR 1.69-3.22 mPa*s) for purulent samples and 3.50 mPa*s (IQR 2.81-3.90 mPa*s) for biliary samples (all differences p < 0.01). Relative to water, dynamic viscosities were increased by a factor of 1.36 for serous fluids, 2.26 for purulent fluids, and 4.03 for biliary fluids. Serous fluids have apparent viscosities similar to water, but biliary and purulent fluids are more viscous. These data can be used as a reference when selecting the drainage catheter size, with 8F catheters being appropriate for most percutaneous drainage cases.

Palliation of malignant dysphagia with a segmented self-expanding metal stent: A STROBE-compliant article.

ABSTRACT: Self-expanding metal stents (SEMSs) in different geometric shapes are an established palliative treatment for malignant tumors of the esophagus. Mechanical properties and stent design have an impact on patient comfort, migration rate, and removability. SEMS with a segmented design (segSEMS) have recently become available on the market, promising new biomechanical properties for stent placement in benign and malignant esophageal diseases. In this study, we evaluated recurrent dysphagia, quality of life as well as technical success and complications for segmented SEMS-implantation in a retrospective study in palliative patients with dysphagia caused by malignant tumors of the esophagus.Between May 2017 and December 2018, patients presented to the interdisciplinary department of endoscopy of the University Hospital Cologne underwent segmented SEMS placement for malignant dysphagia. Patient follow-up was evaluated, and complications were monitored. Quality of life and functional improvement were monitored using the EORTC QLQ-C30 and QLQ-OE18.A total of 20 consecutive patients (16 men, 4 women; mean age: 65.5, range: 46-82) participated in the study and were treated with 20 segSEMS in total. The success rate of stent placement was 100%. Stent migration occurred in 3 patients (15.0%). Insertion of segSEMS immediately lead to a 48.0% reduction of dysphagia in the first 2 months (P < .001). Pain while eating (odynophagia) could also be significantly reduced by 39.6% over the first 2 months (P < .001).Implantation of segSEMS is a feasible and effective treatment for dysphagia in palliative patients with malignant tumors of the esophagus, offering immediate relief of symptoms and gain of physical functions.

A Novel Hybrid Stent with Endoscopic Vacuum Therapy for Treating Leaks of the Upper Gastrointestinal Tract.

INTRODUCTION: Self-expanding metal stents (SEMS) are an established option for treating leaks in the upper gastrointestinal tract, and endoscopic vacuum therapy (EVT) has become a promising alternative. A novel approach is the use of an esophageal hybrid SEMS (VACStent®), which can maintain esophageal passage during EVT. We present the first study demonstrating successful use of the VACStent® for treating leaks of the upper gastrointestinal tract. METHOD: We performed a retrospective, single-center study of all patients who underwent endoscopic stenting with the VACStent® of leaks in the upper gastrointestinal tract. RESULTS: Indications for treatment with the VACStent® were: iatrogenic esophageal perforation (n = 1), spontaneous perforation (n = 2), esophageal fistula (n = 2), and anastomotic leak after upper gastrointestinal surgery (n = 5). Successful application of the VACStent® was achieved in all patients (n = 10; 100%) with a total of 15 interventions. VACStent® therapy was used as a first-line treatment in 5 patient (success rate 80%; 4 out 5 patients) and as a second-line treatment after failed previous endoscopic therapy in 5 patients (success rate 60%; 3 out of 5 patients). Overall, VACStent® treatment was successful in 70% of the patients (7 out of 10). No severe VACStent® treatment-related adverse events occurred. CONCLUSION: The initial experience has been that the technical application of the VACStent® is safe and technically feasible. However, due to the small number of patients this study could not show the clear advantages of this novel hybrid stent. More studies are necessary to show significant advantages.

[Spontaneously reversible portal vein thrombosis complicating acute pancreatits--computed tomographic findings]. / Computertomographische Verlaufsbeobachtungen der spontanen Rückbildung von Portalvenenthrombosen bei akuter Pankreatitis.

Portal vein thrombosis complicating acute pancreatitis is more often diagnosed today due to the improved imaging techniques (computed tomography, ultrasound, nmr). Nevertheless the outcome of recent portal vein thrombosis is ill-known. We report on the computed tomographic findings and clinical course of portal vein thrombosis in two patients suffering from acute pancreatitis. Both patients showed spontaneous recanalization of the thrombosis.

Somatosensory coding of roughness: the effect of texture adaptation in direct and indirect touch.

To examine somatosensory mechanisms contributing to the perception of roughness, subjects examined surfaces with rigorously specified spatial textures under conditions of direct moving contact between the fingertip and the surface (direct touch) and contact through a rigid probe (indirect touch). Subjects were trained to scan the surfaces along a consistent path and with a speed of 2.7 cm/s. With each mode of touch, periods of prolonged inspection of a single adapting surface were followed by shorter periods in which the roughness of multiple test surfaces was reported. Adaptation caused a drop in perceived roughness under conditions of indirect touch, reflecting the reduced sensitivity of vibrotactile mechanisms that are the main recipients of textural information transmitted through the probe. During direct touch, adaptation had no significant effect on the perception of textures with spatial period >200 mum, which are spatially encoded. The results have an important implication for the physiological basis of the spatial code, which is believed to involve somatosensory cortical neurons with highly structured receptive fields: these cortical populations appear to be less susceptible to adaptation than otherwise similar neuronal populations in the visual system.

Regulation of the endothelial apelin/APJ system by hemodynamic fluid flow.

Although the apelin/APJ system is abundantly expressed in vascular endothelial cells (EC), it has not yet been considered to be regulated by fluid flow. The aim of this study was to explore the influence of shear stress on the expression of apelin/APJ in human EC. Therefore, gene and protein expression were assessed after flow exposure; cell supernatants were collected for measurements of NO and apelin; APJ or apelin knockdown were performed using siRNA. Our data show that gene and protein expression of apelin and APJ are modulated by fluid flow depending on the magnitude of shear stress. Moreover, apelin-12 activated NO production via PI3K/Akt signaling in human EC. In contrast, apelin-13 additionally activated Erk1/2 phosphorylation and enhanced EC proliferation. Knockdown of APJ inhibited phosphorylation of PI3K and impaired flow-induced eNOS and PECAM-1 expression. Knockdown of apelin had no influence on flow-induced APJ and PECAM-1 expression, but derogated eNOS expression under static and flow conditions. The present study reveals a flow-mediated adjustment of the apelin/APJ system in human EC in which APJ expression is induced by shear stress independently of its ligand. Furthermore, apelin-12 signaling is an essential regulatory element in endothelial NO synthesis.

Factors contributing to the integration of textural qualities: evidence from virtual surfaces.

Two experiments involving indirect touch were carried out to explore the relationships among perceptual dimensions of haptically examined surfaces. Subjects in both experiments used a stylus to evaluate the properties of virtual surfaces created by a force-feedback device; four surface properties (resistance to normal force, coefficient of friction, texture scale, and vibration amplitude) were manipulated in various combinations. In Experiment 1, the extent to which there was a one-to-one relationship between specific stimulus properties and perceptual qualities ("perceptual separability") was evaluated. A substantial failure of separability was demonstrated, with friction tending to be more separable from the other properties than they were from one another. The pattern of results suggests that the amount of measured separability depends crucially on the way stimulus properties are defined (e.g., force versus displacement). In Experiment 2, surfaces with known perceptual properties were used to study the metric(s) of the relevant perceptual space. By specifying the perceptual, rather than the stimulus, coordinates of the surfaces, it was possible to bypass issues of perceptual separability. For surfaces of equal friction, a Euclidean metric captured the results (r(2) = 0.75) more effectively than a city-block metric did; neither metric did well when differences in friction were involved. The fact that-unlike stickiness-hardness, roughness, and perceived vibration intensity are all increasing functions of surface-normal forces may facilitate their integration into a Euclidean space, in both direct and indirect touch.