Placental volume, thickness and transverse relaxation time (T2*) estimated by magnetic resonance imaging in relation to small for gestational age at birth.

INTRODUCTION: Placental magnetic resonance imaging (MRI) may be a valuable tool in the prediction of small for gestational age (SGA) at birth. MRI provides reliable estimates of placental volume and thickness. In addition, placental transverse relaxation time (T2*) may be directly related to placental function. This study aimed to explore and compare the predictive performance of three placental MRI parameters - volume, thickness and T2* - in relation to SGA at birth. METHODS: A mixed cohort of 85 pregnancies was retrieved from the placental MRI database at the study hospital. MRI was performed in a 1.5 T system at gestational weeks 15-41. In normal birthweight (BW) pregnancies [BW > -22 % of expected for gestational age (GA)], the correlation between each of the MRI parameters and GA was investigated by linear regression. The prediction of SGA was investigated by logistic regression analysis adjusted for GA at MRI. RESULTS: In normal BW pregnancies, a significant linear correlation was found between GA and each of the MRI parameters. Univariate analysis demonstrated that placental volume [odds ratio (OR) 0.97, p = 0.001] and placental T2* (OR 0.79, p = 0.003), but not placental thickness (OR 0.92, p = 0.862) were significant predictors of SGA. A multi-variate model including all three MRI parameters found that placental T2* was the only independent predictor of SGA (OR 0.81, p = 0.04). CONCLUSION: Among the MRI parameters investigated in this study, placental T2* was the only independent predictor of SGA in a multi-variate model. This finding underlines the strong position of T2*-weighted placental MRI in the prediction of SGA.

The Mars Environmental Dynamics Analyzer, MEDA. A Suite of Environmental Sensors for the Mars 2020 Mission.

NASA's Mars 2020 (M2020) rover mission includes a suite of sensors to monitor current environmental conditions near the surface of Mars and to constrain bulk aerosol properties from changes in atmospheric radiation at the surface. The Mars Environmental Dynamics Analyzer (MEDA) consists of a set of meteorological sensors including wind sensor, a barometer, a relative humidity sensor, a set of 5 thermocouples to measure atmospheric temperature at ∼1.5 m and ∼0.5 m above the surface, a set of thermopiles to characterize the thermal IR brightness temperatures of the surface and the lower atmosphere. MEDA adds a radiation and dust sensor to monitor the optical atmospheric properties that can be used to infer bulk aerosol physical properties such as particle size distribution, non-sphericity, and concentration. The MEDA package and its scientific purpose are described in this document as well as how it responded to the calibration tests and how it helps prepare for the human exploration of Mars. A comparison is also presented to previous environmental monitoring payloads landed on Mars on the Viking, Pathfinder, Phoenix, MSL, and InSight spacecraft.

SuperCam Calibration Targets: Design and Development.

SuperCam is a highly integrated remote-sensing instrumental suite for NASA's Mars 2020 mission. It consists of a co-aligned combination of Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), Visible and Infrared Spectroscopy (VISIR), together with sound recording (MIC) and high-magnification imaging techniques (RMI). They provide information on the mineralogy, geochemistry and mineral context around the Perseverance Rover. The calibration of this complex suite is a major challenge. Not only does each technique require its own standards or references, their combination also introduces new requirements to obtain optimal scientific output. Elemental composition, molecular vibrational features, fluorescence, morphology and texture provide a full picture of the sample with spectral information that needs to be co-aligned, correlated, and individually calibrated. The resulting hardware includes different kinds of targets, each one covering different needs of the instrument. Standards for imaging calibration, geological samples for mineral identification and chemometric calculations or spectral references to calibrate and evaluate the health of the instrument, are all included in the SuperCam Calibration Target (SCCT). The system also includes a specifically designed assembly in which the samples are mounted. This hardware allows the targets to survive the harsh environmental conditions of the launch, cruise, landing and operation on Mars during the whole mission. Here we summarize the design, development, integration, verification and functional testing of the SCCT. This work includes some key results obtained to verify the scientific outcome of the SuperCam system.

15O-water PET for evaluation of cardiopulmonary perfusion in complex cyanotic heart disease.

BACKGROUND: Dynamic 15O-water PET may provide information about cardiopulmonary circulation complementary to MRI and CT in complex cyanotic heart disease. CASE PRESENTATION: We present a case in which a 15O-water PET scan was used for the first time to map the complex circulation in a univentricular heart patient with dual pulmonary blood supply. The pulmonary blood supply consisted of partially oxygenated blood led from the univentricle to the lungs by the pulmonary artery, plus of venous blood from the upper body lead by a bidirectional Glenn anastomosis to the right pulmonary artery. Despite the bidirectional Glenn anastomosis, the patient developed increasing cyanosis and was considered for heart transplantation. Pulmonary perfusion measurements using MRI were inconclusive due to metal artifacts, and the patient was referred for a 15O-water PET scan. The scan showed significant venovenous collaterals bypassing the lungs. Only the left upper lung lobe was properly perfused. The mean transit time from the superior vena cava to the left ventricle was approximately four times longer than would be expected from a healthy person. CONCLUSION: The case illustrates that 15O-water PET can complement CT and MRI for quantitative characterization of cardiopulmonary circulation in complex cyanotic heart disease.

Tissue viscoelasticity is related to tissue composition but may not fully predict the apparent-level viscoelasticity in human trabecular bone - An experimental and finite element study.

Trabecular bone is viscoelastic under dynamic loading. However, it is unclear how tissue viscoelasticity controls viscoelasticity at the apparent-level. In this study, viscoelasticity of cylindrical human trabecular bone samples (n=11, male, age 18-78 years) from 11 proximal femurs were characterized using dynamic and stress-relaxation testing at the apparent-level and with creep nanoindentation at the tissue-level. In addition, bone tissue elasticity was determined using scanning acoustic microscope (SAM). Tissue composition and collagen crosslinks were assessed using Raman micro-spectroscopy and high performance liquid chromatography (HPLC), respectively. Values of material parameters were obtained from finite element (FE) models by optimizing tissue-level creep and apparent-level stress-relaxation to experimental nanoindentation and unconfined compression testing values, respectively, utilizing the second order Prony series to depict viscoelasticity. FE simulations showed that tissue-level equilibrium elastic modulus (Eeq) increased with increasing crystallinity (r=0.730, p=.011) while at the apparent-level it increased with increasing hydroxylysyl pyridinoline content (r=0.718, p=.019). In addition, the normalized shear modulus g1 (r=-0.780, p=.005) decreased with increasing collagen ratio (amide III/CH2) at the tissue-level, but increased (r=0.696, p=.025) with increasing collagen ratio at the apparent-level. No significant relations were found between the measured or simulated viscoelastic parameters at the tissue- and apparent-levels nor were the parameters related to tissue elasticity determined with SAM. However, only Eeq, g2 and relaxation time τ1 from simulated viscoelastic values were statistically different between tissue- and apparent-levels (p<.01). These findings indicate that bone tissue viscoelasticity is affected by tissue composition but may not fully predict the macroscale viscoelasticity in human trabecular bone.

A novel combination of peripheral nerve blocks for arthroscopic shoulder surgery.

BACKGROUND: Interscalene brachial plexus block is currently the gold standard for intra- and post-operative pain management for patients undergoing arthroscopic shoulder surgery. However, it is associated with block related complications, of which effect on the phrenic nerve have been of most interest. Side effects caused by general anesthesia, when this is required, are also a concern. We hypothesized that the combination of superficial cervical plexus block, suprascapular nerve block, and infraclavicular brachial plexus block would provide a good alternative to interscalene block and general anesthesia. METHODS: Twenty adult patients scheduled for arthroscopic shoulder surgery received a combination of superficial cervical plexus block (5 ml ropivacaine 0.5%), suprascapular nerve block (4 ml ropivacaine 0.5%), and lateral sagittal infraclavicular block (31 ml ropivacaine 0.75%). The primary aim was to find the proportion of patients who could be operated under light propofol sedation, without the need for opioids or artificial airway. Secondary aims were patients' satisfaction and surgeons' judgment of the operating conditions. RESULTS: Nineteen of twenty patients (95% CI: 85-100) underwent arthroscopic shoulder surgery with light propofol sedation, but without opioids or artificial airway. The excluded patient was not comfortable in the beach chair position and therefore received general anesthesia. All patients were satisfied with the treatment on follow-up interviews. The surgeons rated the operating conditions as good for all patients. CONCLUSION: The novel combination of a superficial cervical plexus block, a suprascapular nerve block, and an infraclavicular nerve block provides an alternative anesthetic modality for arthroscopic shoulder surgery.

Pain and pain mechanisms in patients with inflammatory arthritis: A Danish nationwide cross-sectional DANBIO registry survey.

BACKGROUND: Central pain mechanisms may be prominent in subsets of patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) and other spondyloarthritis (SpA). The painDETECT questionnaire (PDQ) identifies neuropathic pain features, which may act as a proxy for centrally mediated pain. The objectives were to quantify and characterize pain phenotypes (non-neuropathic vs. neuropathic features) among Danish arthritis patients using the PDQ, and to assess the association with on-going inflammation. METHODS: The PDQ was included onto the DANBIO touch screens at 22 departments of Rheumatology in Denmark for six months. Clinical data and patient reported outcomes were obtained from DANBIO. A PDQ-score >18 indicated neuropathic pain features, 13-18 unclear pain mechanism and <13 non-neuropathic pain. RESULTS: Pain data (visual analogue scale, VAS) was available for 15,978 patients. 7,054 patients completed the PDQ (RA: 3,826, PsA: 1,180, SpA: 1,093). 52% of all patients and 63% of PDQ-completers had VAS pain score ≥ 30 mm. The distribution of the PDQ classification-groups (<13/ 13-18/ >18) were; RA: 56%/24%/20%. PsA: 45%/ 27%/ 28%. SpA: 55% / 24%/ 21%. More patients with PsA had PDQ score >18 compared to RA and SpA (p<0.001). For PDQ > 18 significantly higher scores were found for all patient reported outcomes and disease activity scores. No clinical difference in CRP or swollen joint count was found. Logistic regression showed increased odds for having VAS pain ≥39 mm (the median) for a PDQ-score >18 compared to <13 (OR = 10.4; 95%CI 8.6-12.5). CONCLUSIONS: More than 50% of the Danish arthritis patients reported clinically significant pain. More than 20% of the PDQ-completers had indication of neuropathic pain features, which was related to a high pain-level. PDQ-score was associated with DAS28-CRP and VAS pain but not with indicators of peripheral inflammation (CRP and SJC). Thus, pain classification by PDQ may assist in mechanism-based pain treatment.

MicroRNAs in metabolism.

MicroRNAs (miRNAs) have within the past decade emerged as key regulators of metabolic homoeostasis. Major tissues in intermediary metabolism important during development of the metabolic syndrome, such as ß-cells, liver, skeletal and heart muscle as well as adipose tissue, have all been shown to be affected by miRNAs. In the pancreatic ß-cell, a number of miRNAs are important in maintaining the balance between differentiation and proliferation (miR-200 and miR-29 families) and insulin exocytosis in the differentiated state is controlled by miR-7, miR-375 and miR-335. MiR-33a and MiR-33b play crucial roles in cholesterol and lipid metabolism, whereas miR-103 and miR-107 regulates hepatic insulin sensitivity. In muscle tissue, a defined number of miRNAs (miR-1, miR-133, miR-206) control myofibre type switch and induce myogenic differentiation programmes. Similarly, in adipose tissue, a defined number of miRNAs control white to brown adipocyte conversion or differentiation (miR-365, miR-133, miR-455). The discovery of circulating miRNAs in exosomes emphasizes their importance as both endocrine signalling molecules and potentially disease markers. Their dysregulation in metabolic diseases, such as obesity, type 2 diabetes and atherosclerosis stresses their potential as therapeutic targets. This review emphasizes current ideas and controversies within miRNA research in metabolism.

A randomised placebo-controlled trial examining the effect on hand supination after the addition of a suprascapular nerve block to infraclavicular brachial plexus blockade.

Some surgeons believe that infraclavicular brachial plexus blocks tends to result in supination of the hand/forearm, which may make surgical access to the dorsum of the hand more difficult. We hypothesised that this supination may be reduced by the addition of a suprascapular nerve block. In a double-blind, randomised, placebo-controlled study, our primary outcome measure was the amount of supination (as assessed by wrist angulation) 30 min after infraclavicular brachial plexus block, with (suprascapular group) or without (control group) a supplementary suprascapular block. All blocks were ultrasound-guided. The secondary outcome measure was an assessment by the surgeon of the intra-operative position of the hand. Considering only patients with successful nerve blocks, mean (SD) wrist angulation was lower (33 (27) vs. 61 (44) degrees; p = 0.018) and assessment of the hand position was better (11/11 vs. 6/11 rated as 'good'; p = 0.04) in the suprascapular group. The addition of a suprascapular nerve block to an infraclavicular brachial plexus block can provide a better hand/forearm position for dorsal hand surgery.

Non-nociceptive pain in rheumatoid arthritis is frequent and affects disease activity estimation: cross-sectional data from the FRAME study.

BACKGROUND: The painDETECT questionnaire (PDQ) is a mechanism-based pain classification tool assigning patients to one of three categories depending on the quality of the experienced pain. Patients with non-nociceptive pain score high on the PDQ. The objective was to assess the proportions of the three PDQ classification groups in patients with rheumatoid arthritis (RA) and to explore differences in clinical characteristics. METHOD: RA patients initiating or escalating their RA therapy were included prospectively and underwent a thorough examination programme. Low (PDQ score < 13), medium (PDQ score 13-18), and high (PDQ score > 18) scores indicate nociceptive, unclear/possible neuropathic, or neuropathic pain mechanisms, respectively. RESULTS: The 102 included patients were classified into the following PDQ classification groups: low = 65%, medium = 23%, and high = 12%. Patients in the medium and high PDQ groups scored worse on indicators of anxiety, depression, disability, mental health-related quality of life, pain, and fatigue. They also had more tender points and an RA disease activity score based on 28 joints (DAS28) where a higher fraction of the composite score pertained to non-inflammatory factors compared to patients in the low PDQ classification group. There were no differences in objective inflammatory indices across groups. Multiple regression analysis demonstrated that the tender joint count (TJC) and the 36-item Short Form Health Survey (SF36) mental component summary (MCS) score were independently associated with the PDQ score. CONCLUSIONS: In patients initiating or intensifying medical treatment for their RA, non-nociceptive pain (PDQ score ≥ 13) is common. In these patients, the pain mechanisms result in increased disease activity scores on a non-inflammatory basis.

Atomic and electronic structure transformations in SnS2 at high pressures: a joint single crystal X-ray diffraction and DFT study.

The layered semiconductor SnS2 spurs much interest for both intercalation and optoelectronic applications. Despite the wealth of research in the field of metal dichalcogenides, the structure-property relationship of this compound remains unclear. Here we present a thorough study combining single-crystal X-ray diffraction and DFT calculations on SnS2 in the pressure range 0 < p < 20 GPa. The anisotropic compression of the unit cell is clearly linked to the van der Waals interactions between the S-Sn-S sandwich layers, as the compression mainly affects the interlayer distance. This compression behavior is coincidal with the compression of other well-known layered compounds (graphite and boron nitride) but differs significantly from the compression of other MS2 compounds, making it clear that SnS2 presents a unique and interesting case in the field of metal dichalcogenides. The compression leads to a significant increase in S···S interlayer interaction which in turn results in a change in the electronic structure, documented through DFT band structure calculations. The calculated narrowing of the band gap is supported by a significant, reversible color change of the single crystal. At 20 GPa, the size of the band gap has decreased from 2.15 to 0.88 eV, and band gap closure is predicted to occur at 33 GPa.

Correlations between fatigue and disease duration, disease activity, and pain in patients with rheumatoid arthritis: a systematic review.

OBJECTIVES: Rheumatoid arthritis (RA) patients suffer from disabling fatigue but the causes of this condition are unknown. Our aim was to assess which of the variables disease activity, disease duration, and pain is associated with fatigue. METHOD: We conducted a systematic literature search in MEDLINE and EMBASE, followed by selection of studies according to set criteria, data extraction, and statistical analyses of the relationships in RA between fatigue and the following covariates: disease duration, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), the 28-joint Disease Activity Score (DAS28), swollen to tender joint count ratio (STR), and pain. Linear regression analyses of fatigue regressed on each of the six covariates, and a multiple regression analysis where fatigue was regressed on the six covariates through a forward selection procedure was carried out with construction of correlation measures between fatigue and the covariates. RESULTS: A total of 121 studies were included in the analyses, including > 100 000 RA patients. A high level of fatigue was seen even in well-treated patients, demonstrating fatigue as a major problem in RA. Fatigue was found to be positively correlated with pain, CRP, DAS28, and ESR but not with the STR or disease duration, with pain as the overall domineering factor. CONCLUSIONS: Fatigue has a substantial influence on the lives of RA patients, independent of disease duration. Pain is the domineering factor in the experience and degree of fatigue. Disease activity is positively correlated to fatigue but does not contribute substantially when pain is considered. Optimal pain relief is therefore an important part of the treatment to improve fatigue in RA.

High-pressure phase transitions in ordered and disordered Bi2Te2Se.

We report studies of pressure-induced phase transitions of ordered and disordered ternary tetradymite-like Bi2Te2Se by synchrotron powder X-ray diffraction (PXRD) in diamond anvil cells (DACs) for pressures up to 59 and 49 GPa, respectively. The first sample (SB) was prepared from a single crystal with ordered Se/Te sites while the second sample (Q) was prepared from a quenched melt resulting in disordered Se/Te. This allows for an investigation of the effect of disorder on the phase transitions and the equation of states (EoS) of the tetradymite-like α phase. Fitting of a third order Birch-Murnaghan EoS to the α phases yielded bulk moduli K0 of 34.5(10) and 38.3(17) GPa and K' of 6.2(3) and 5.0(5) for the SB and Q samples, respectively. An electronic topological transition (ETT) was identified in both samples at pressures of 4.4 and 3.1 GPa, respectively. This was followed by a transition near 11 GPa to a phase that is isostructural with the ß phase of Bi2Te3. The Se/Te ordering only affects the transition pressure to a small extent. A cubic phase that resembles the δ phase observed in high-pressure studies of Bi2Te3 appears at 17-20 GPa, but the ternary composition leads to a more complex structure. The presence of a low angle diffraction peak in the δ phase demonstrates that the true structure is not simply body-centred cubic. In this way the samples resemble Bi2Se3 where Bi and Se show a high degree of ordering, but the proposed structure of δ-Bi2Se3 also does not fully describe the data for δ-Bi2Te2Se.

High-pressure single crystal X-ray diffraction study of the linear metal chain compound Co3(dpa)4Br2·CH2Cl2.

The crystal structure of the linear metal chain compound Co3(dpa)4Br2·CH2Cl2 (1) has been investigated up to a pressure of 13.6(2) GPa in a diamond anvil cell (DAC) using single crystal X-ray diffraction. The structure remains orthorhombic as the unit cell volume is reduced by 30% at 12.8 GPa. At 13.6(2) GPa the diffraction pattern is of very poor quality and not even reliable unit cell parameters can be determined. Peak broadening resulting from non-hydrostatic conditions was avoided by annealing the loaded DAC prior to data collection, allowing reliable structural models to be refined up to a pressure of 11.8(2) GPa. On increasing pressure, the disordered CH2Cl2 crystal solvent molecule gradually becomes redistributed from one site to another. Hirshfeld surface analysis suggests that the redistribution is a result of repulsive HH interactions. Pressure also affects the molecular geometry, in particular the Co-Co and Co-Br bond lengths which decrease by 4% and 12%, respectively, at 11.8(2) GPa.

Minimum effective volume of ropivacaine 7.5 mg/ml for an ultrasound-guided infraclavicular brachial plexus block.

BACKGROUND: Ultrasound guidance has been shown to reduce the minimum effective volume (MEV) of local anaesthetics for several peripheral nerve blocks. Although the lateral sagittal infraclavicular block (LSIB) is a well-established anaesthesia method, MEV for this technique has not been established. Our aim with this study was to determine the MEV using ropivacaine 7.5 mg/ml for the LSIB method. METHODS: Twenty-five adult American Society of Anesthesiologists physical status I-II patients scheduled for hand surgery received an ultrasound-guided LSIB with ropivacaine 7.5 mg/ml. A successful block was defined as anaesthesia or analgesia for all five sensory nerves distal to the elbow, 30 min after local anaesthetic injection. The MEV for a successful block in 50% of the patients was determined by using the staircase up-and-down method introduced by Dixon and Massey. Logistic regression and probit transformation were applied to estimate the MEV for a successful block in 95% of the patients. RESULTS: The patients received ropivacaine 7.5 mg/ml volumes in the range of 12.5-30 ml. The MEVs in 50% and 95% of the patients were 19 ml [95% confidence interval (CI), 14-27] and 31 ml (95% CI, 18-45), respectively. CONCLUSIONS: For surgery distal to the elbow, the MEV in 95% of patients for an ultrasound-guided LSIB with ropivacaine 7.5 mg/ml was estimated to be 31 ml (95% CI, 18-45 ml). Further studies should determine the factors that influence the volume of local anaesthetic required for a successful infraclavicular block.

Analytical and numerical modelling of Newtonian and non-Newtonian liquid in a rotational cross-flow MBR.

Fouling is the main bottleneck of the widespread use of MBR systems. One way to decrease and/or control fouling is by process hydrodynamics. This can be achieved by the increase of liquid cross-flow velocity. In rotational cross-flow MBR systems, this is attained by the spinning of, for example, impellers. Validation of the CFD (computational fluid dynamics) model was made against laser Doppler anemometry (LDA) tangential velocity measurements (error less than 8%) using water as a fluid. The shear stress over the membrane surface was inferred from the CFD simulations for water. However, activated sludge (AS) is a non-Newtonian liquid, for which the CFD model was modified incorporating the non-Newtonian behaviour of AS. Shear stress and area-weighted average shear stress relationships were made giving error less that 8% compared with the CFD results. An empirical relationship for the area-weighted average shear stress was developed for water and AS as a function of the angular velocity and the total suspended solids concentration. These relationships can be linked to the energy consumption of this type of systems.

Tricellulin, occludin and claudin-3 expression in salmon intestine and kidney during salinity adaptation.

Molecular regulation of tight junctions in osmoregulatory epithelia of euryhaline fishes must be extensive during ontogeny and acclimation to salinity changes. In this study, five tight junction proteins were examined in Atlantic salmon (Salmo salar): tight junction associated tricellulin, occludin and claudin-3 isoforms (a, b, c). A survey of tissue distribution in freshwater (FW) salmon showed that tricellulin expression was highest in the intestine. Occludin was detected in tissues with importance for epithelial transport and the order of expression was gill>intestine>kidney. The three claudin-3 isoforms were expressed at highest level in kidney tissue. Transfer of juvenile FW salmon to seawater (SW) elevated intestinal tricellulin and occludin mRNA, and these transcripts were also elevated at the time of best SW-tolerance during the course of smoltification. In the kidney, expression of tricellulin and claudin-3 isoforms was elevated after SW-transfer and tricellulin, occludin, claudin-3a and -3b increased in March before the peak smolt stage. In the gill, none of the examined tight junction proteins were impacted by SW-transfer. The data suggest that expression of tricellulin and occludin is dynamically involved in reorganization of intestinal epithelium and possibly changed paracellular permeability during SW-acclimation. The increased renal tricellulin and claudin-3 expression in SW suggests a role in remodeling of the kidney during SW-acclimation.

Increased incidence of Mycoplasma pneumoniae infection in Norway 2011.

Epidemics of Mycoplasma pneumoniae have recently been reported from England and Wales and from Denmark. A similar increase in M. pneumoniae infections was noted in Norway late autumn 2011.The epidemic has resulted in shortage of erythromycin and the use of alternative antibiotics has been recommended.

Functional characterization and localization of a gill-specific claudin isoform in Atlantic salmon.

Claudins are the major determinants of paracellular epithelial permeability in multicellular organisms. In Atlantic salmon (Salmo salar L.), we previously found that mRNA expression of the abundant gill-specific claudin 30 decreases during seawater (SW) acclimation, suggesting that this claudin is associated with remodeling of the epithelium during salinity change. This study investigated localization, protein expression, and function of claudin 30. Confocal microscopy showed that claudin 30 protein was located at cell-cell interfaces in the gill filament in SW- and fresh water (FW)-acclimated salmon, with the same distribution, overall, as the tight junction protein ZO-1. Claudin 30 was located at the apical tight junction interface and in cell membranes deeper in the epithelia. Colocalization with the α-subunit of the Na(+)-K(+)-ATPase was negligible, suggesting limited association with mitochondria-rich cells. Immunoblotting of gill samples showed lower claudin 30 protein expression in SW than FW fish. Retroviral transduction of claudin 30 into Madin-Darby canine kidney cells resulted in a decreased conductance of 19%. The decreased conductance correlated with a decreased permeability of the cell monolayer to monovalent cations, whereas permeability to chloride was unaffected. Confocal microscopy revealed that claudin 30 was expressed in the lateral membrane, as well as in tight junctions of Madin-Darby canine kidney cells, thereby paralleling the findings in the native gill. This study suggests that claudin 30 functions as a cation barrier between pavement cells in the gill and also has a general role in cell-cell adhesion in deeper layers of the epithelium.