Follow-up evaluation of patients with liver test abnormalities detected during SARS-CoV2 infection

Abnormal liver function tests (A-LFTs) during admission for coronavirus disease-19 (COVID-19) are frequent, but its evolution after COVID-19 resolution remains unexplored. We evaluated factors related to A-LFTs during COVID-19 and assessed the liver outcome after patients' discharge. This is a observational study including: (1) retrospective analysis of variables related to A-LFTs during COVID-19; and (2) follow-up evaluation with blood test, transient elastography and liver biopsy in those with persistent A-LFTs. A-LFTs were defined according to CTCAEv4.0. Among 595 patients, 366 (61.5%) showed A-LFTs. The ratio of partial pressure of oxygen and inspired oxygen fraction (P/F) below 200, ferritin ≥1000 ng/mL, male gender and antibiotic and immunomodulatory treatments were related to A-LFTs. Follow-up evaluation was performed in 153 individuals. Persistent A-LFTs at follow-up was similar in patients with/without A-LFTs during admission (14.1% vs. 4.9%, p = 0.104). Fifteen (93%) and 58 (39%) patients with/without A-LFTs at follow-up showed metabolic fatty liver disease criteria (p < 0.001), which were histologically confirmed. In conclusion, A-LFTs during COVID-19 were related to infection severity. Abnormalities remitted at follow-up in >80% of patients, and no correlation between A-LFTs at admission and at follow-up was found. Most patients with A-LFTs at follow-up had non-invasive and histologically proven fatty liver disease.

Podocytopathy in patients with monoclonal gammopathy: three patients and literature review

BACKGROUND

Renal manifestations of monoclonal gammopathies are of increasing interest among nephrologists. Typical manifestations include light chain cast nephropathy, amyloidosis or renal damage mediated by monoclonal immunoglobulin deposition. Podocytopathies in the setting of an underlying monoclonal gammopathy constitute a rare manifestation of these diseases and, although being described in the literature, remain a challenge since most data derive from case reports.

METHODS

A retrospective review of the clinical data of Hospital del Mar and Hospital Vall d'Hebron was performed to identify patients with minimal change disease (MCD) or focal and segmental glomerulosclerosis (FSGS) in the setting of neoplasms that produce monoclonal (M) protein. Additionally, a literature review on this topic was performed. This study aims to describe the clinical characteristics and outcomes of these patients.

RESULTS

Three patients were identified to have podocytopathy and monoclonal gammopathy between the years 2013 and 2020. All three were males and  >65 years of age. Two patients were diagnosed with MCD and one patient was diagnosed with FSGS. All patients underwent a kidney biopsy and light and electron microscopic studies were performed. The underlying causes of monoclonal gammopathy were multiple myeloma in two cases and Waldeström macroglobulinemia in one case. Two patients developed nephrotic syndrome during the follow-up. All patients were under active hematological treatment. One patient presented a complete remission of proteinuria whereas the other two presented a partial remission.

CONCLUSIONS

Podocytopathies may infrequently be found in patients with monoclonal gammopathies. Patients with overt glomerular proteinuria and hematological disorders with M protein should undergo a kidney biopsy for prompt diagnosis and to specify a prognosis. In addition, further study on this matter must be done to understand the pathophysiology and treat these patients appropriately.

Elastography is unable to exclude cirrhosis after sustained virological response in HCV-infected patients with advanced chronic liver disease

BACKGROUND

Liver fibrosis and transient elastography (TE) correlation in hepatitis C virus (HCV)-infected patients with compensated advanced chronic liver disease (cACLD) after the sustained virological response (SVR) is unknown.

AIMS

To evaluate TE accuracy at identifying cirrhosis 3 years after HCV-eradication.

METHODS

Prospective, multi-centric study including HCV-cACLD patients before direct-acting antivirals (DAA). Diagnostic accuracy of TE (area under ROC, AUROC) to identify cirrhosis 3 years after SVR was evaluated.

RESULTS

Among 746 HCV-infected patients (95.4% with TE ≥10 kPa), 76 (10.2%) underwent a liver biopsy 3 years after SVR. Before treatment, 46 (63%) showed a TE>15 kPa. The TE before DAA was the best variable for predicting cirrhosis (METAVIR, F4) after SVR (AUROC = 0.79). Liver function parameters, serological non-invasive tests (APRI and FIB-4), and TE values improved after SVR. However, liver biopsy 3 years after HCV elimination (median time = 38.4 months) showed cirrhosis in 41 (53.9%). Multivariate analysis (OR (95% CI), P) showed that HCV-genotype 3 (20.81 (2.12-201.47), .009), and TE before treatment (1.21 (1.09-1.34), <.001) were the only variables associated with cirrhosis after SVR. However, the accuracy of TE after SVR was poor (AUROC = 0.75) and 6 (27.3%) out of 22 patients with a TE <8 kPa had cirrhosis. Similar results were found with APRI and FIB-4 scores.

CONCLUSIONS

Cirrhosis is present, 3 years after SVR, in more than half of HCV-cACLD patients even with the normalisation of liver function parameters, serological non-invasive tests and TE values. The low diagnostic accuracy of non-invasive methods after SVR reinforces the need for long-term surveillance.

Narrow-band imaging and high-definition white-light endoscopy in patients with serrated lesions not fulfilling criteria for serrated polyposis syndrome: a randomized controlled trial with tandem colonoscopy

BACKGROUND

It is unknown whether narrow-band imaging (NBI) could be more effective than high-definition white-light endoscopy (HD-WLE) in detecting serrated lesions in patients with prior serrated lesions > 5 mm not completely fulfilling serrated polyposis syndrome (SPS) criteria.

METHODS

We conducted a randomized, cross-over trial in consecutive patients with prior detection of at least one serrated polyp ≥10 mm or ≥ 3 serrated polyps larger than 5 mm, both proximal to the sigmoid colon. Five experienced endoscopists performed same-day tandem colonoscopies, with the order being randomized 1:1 to NBI-HD-WLE or HD-WLE-NBI. All tandem colonoscopies were performed by the same endoscopist.

RESULTS

We included 41 patients. Baseline characteristics were similar in the two cohorts: NBI-HD-WLE (n = 21) and HD-WLE-NBI (n = 20). No differences were observed in the serrated lesion detection rate of NBI versus HD-WLE: 47.4% versus 51.9% (OR 0.84, 95% CI: 0.37-1.91) for the first and second withdrawal, respectively. Equally, no differences were found in the polyp miss rate of NBI versus HD-WLE: 21.3% versus 26.1% (OR 0.77, 95% CI: 0.43-1.38). Follow-up colonoscopy in nine patients (22%) allowed them to be reclassified as having SPS.

CONCLUSIONS

In patients with previous serrated lesions, the serrated lesion detection rate was similar with NBI and HD-WLE. A shorter surveillance colonoscopy interval increases the detection of missed serrated polyps and could change the diagnosis of SPS in approximately one in every five patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02406547, registered on April 2, 2015.

Monetary reinforcement for self-monitoring of blood glucose among young people with type 1 diabetes: evaluating effects on psychosocial functioning

AIMS

To explore the auxiliary psychosocial effects of a monetary reinforcement intervention targeting self-monitoring of blood glucose among young people with Type 1 diabetes.

METHODS

Sixty young people with Type 1 diabetes, HbA_1c concentrations between 58 and 119 mmol/mol (7.5-13.0%), and average self-monitoring of blood glucose <4 times per day were randomized to either enhanced usual care or a 24-week intervention of monetary rewards for self-monitoring of blood glucose and associated behaviours (e.g. uploading glucose meters). Data were collected from the young people and their parents at baseline, during the intervention (6, 12 and 24 weeks) and after the intervention (36 weeks).

RESULTS

Linear mixed models were used to evaluate the intervention effects on psychosocial outcomes, adjusting for corresponding baseline levels and potential moderation by baseline level. The intervention reduced diabetes distress at week 6 among young people who had average and high baseline distress. It also reduced diabetes distress at weeks 12 and 24 among those with low baseline distress. The intervention also reduced young person-reported diabetes-related family conflict and diabetes-related interference among those with high baseline scores in these areas; however, the intervention worsened young person-reported diabetes interference among those with low baseline interference. Effects were medium-sized and time-limited.

CONCLUSIONS

Findings indicate predominantly positive impacts of monetary reinforcement interventions on psychosocial outcomes, although effects varied by outcome and time point. Whereas early improvements in diabetes distress were observed for all who received the intervention, improvements in other areas varied according to the level of psychosocial challenge at baseline. Incorporating psychosocial interventions may bolster and maintain effects over time.

Assessing patient-reported outcomes for automated insulin delivery systems: the psychometric properties of the INSPIRE measures

AIM

Participants in clinical trials assessing automated insulin delivery systems report perceived benefits and burdens that reflect their experiences and may predict their likelihood of uptake and continued use of this novel technology. Despite the importance of understanding their perspectives, there are no available validated and reliable measures assessing the psychosocial aspects of automated insulin delivery systems. The present study assesses the initial psychometric properties of the INSPIRE measures, which were developed for youth and adults with Type 1 diabetes, as well as parents and partners.

METHODS

Data from 292 youth, 159 adults, 150 parents of youth and 149 partners of individuals recruited from the Type 1 Diabetes Exchange Registry were analysed. Participants completed INSPIRE questionnaires and measures of quality of life, fear of hypoglycaemia, diabetes distress, glucose monitoring satisfaction. Exploratory factor analysis assessed factor structures. Associations between INSPIRE scores and other measures, HbA_1c , and technology use assessed concurrent and discriminant validity.

RESULTS

Youth, adult, parent and partner measures assess positive expectancies of automated insulin delivery systems. Measures range from 17 to 22 items and are reliable (α = 0.95-0.97). Youth, adult and parent measures are unidimensional; the partner measure has a two-factor structure (perceptions of impact on partners versus the person with diabetes). Measures showed concurrent and discriminant validity.

CONCLUSIONS

INSPIRE measures assessing the positive expectancies of automated insulin delivery systems for youth, adults, parents and partners have meaningful factor structures and are internally consistent. The developmentally sensitive INSPIRE measures offer added value as clinical trials test newer systems, systems become commercially available and clinicians initiate using these systems.

Focused Transhepatic Electroporation Mediated by Hypersaline Infusion through the Portal Vein in Rat Model. Preliminary Results on Differential Conductivity

Background

Spread hepatic tumours are not suitable for treatment either by surgery or conventional ablation methods. The aim of this study was to evaluate feasibility and safety of selectively increasing the healthy hepatic conductivity by the hypersaline infusion (HI) through the portal vein. We hypothesize this will allow simultaneous safe treatment of all nodules by irreversible electroporation (IRE) when applied in a transhepatic fashion.

Material and methods

Sprague Dawley (Group A, n = 10) and Athymic rats with implanted hepatic tumour (Group B, n = 8) were employed. HI was performed (NaCl 20%, 3.8 mL/Kg) by trans-splenic puncture. Deionized serum (40 mL/Kg) and furosemide (2 mL/Kg) were simultaneously infused through the jugular vein to compensate hypernatremia. Changes in conductivity were monitored in the hepatic and tumour tissue. The period in which hepatic conductivity was higher than tumour conductivity was defined as the therapeutic window (TW). Animals were monitored during 1-month follow-up. The animals were sacrificed and selective samples were used for histological analysis.

Results

The overall survival rate was 82.4% after the HI protocol. The mean maximum hepatic conductivity after HI was 2.7 and 3.5 times higher than the baseline value, in group A and B, respectively. The mean maximum hepatic conductivity after HI was 1.4 times higher than tumour tissue in group B creating a TW to implement selective IRE.

Conclusions

HI through the portal vein is safe when the hypersaline overload is compensated with deionized serum and it may provide a TW for focused IRE treatment on tumour nodules.

Maternal hypothyroxinemia impairs spatial learning and synaptic nature and function in the offspring

Neurological deficits in the offspring caused by human maternal hypothyroxinemia are thought to be irreversible. To understand the mechanism responsible for these neurological alterations, we induced maternal hypothyroxinemia in pregnant rats. Behavior and synapse function were evaluated in the offspring of thyroid hormone-deficient rats. Our data indicate that, when compared with controls, hypothyroxinemic mothers bear litters that, in adulthood, show prolonged latencies during the learning process in the water maze test. Impaired learning capacity caused by hypothyroxinemia was consistent with cellular and molecular alterations, including: 1) lack of increase of phosphorylated c-fos on the second day of the water maze test; 2) impaired induction of long-term potentiation in response to theta-burst stimulation to the Schaffer collateral pathway in the area 1 of the hippocampus Ammon's horn stratum radiatum, despite normal responses for input/output experiments; 3) increase of postsynaptic density protein 95 (PSD-95), N-methyl-D-aspartic acid receptor subunit 1, and tyrosine receptor kinase B levels in brain extracts; and 4) significant increase of PSD-95 at the PSDs and failure of this molecule to colocalize with N-methyl-D-aspartic acid receptor subunit 1, as it was shown by control rats. Our findings suggest that maternal hypothyroxinemia is a harmful condition for the offspring that can affect key molecular components for synaptic function and spatial learning.

Application of receiver operating characteristics curve (ROC) analysis when definitive and suspect morphologic flags appear in the new Coulter LH 750 analyzer

Workflow efficiency is important in every laboratory. Manual assessment of white blood cell counts and differentials that have been rejected by an automated analyzer is one of the most time-consuming tasks in the routine hematology laboratory. In this study, receiver operating characteristics (ROC) curve analysis was used for the first time when anomalous distribution and suspect flag alarms appeared in hemograms carried out with the new Beckman Coulter LH 750 analyzer. This article is our second about the LH 750 analyzer published in this journal; we increased the number of cases and describe the novel application of statistical analysis of ROC curves. In processing of specimens from patients with 3% to 6% immature granulocytes (myelocytes + metamyelocytes + bands ), the suspect flag Imm Ne 1 (immature granulocytes) showed 77% diagnostic efficiency with a maximum area under curve (AUC) of 0.71 and a 95% confidence interval (CI) of 0.597 to 0.831 without significant differences between the 3 available levels of alarms in the analyzer (L1, L2, L2). In processing of specimens from patients with >6% immature granulocytes, the Imm Ne 1 flag showed superior diagnostic efficiency of 98% with a maximum AUC of 0.80 and a CI of 0.713 to 0.879. The suspect flag Imm Ne 2 in processing of specimens from patients with >6% of immature granulocytes showed diagnostic efficiency of 92% with a maximum AUC of 0.77 and a CI of 0.665 to 0.871, finding a significant positive difference in level L3 regarding sensitivity in comparison with the other 2 levels of the analyzer (L1, L2). For specimens from patients with >2% blasts, the suspect Blasts alarm showed a diagnostic efficiency of 94%, an AUC of 0.91, and a CI of 0.775 to 1.043; positive differences were observed between the levels L2/L3 and L1. In processing of specimens with variant lymphocytes (large, granular, prolymphocytes, cleaved, chronic lymphocytic leukemia type, and so forth) >10% (x = 14%), the suspect alarm Var Lym (variant lymphocytes) showed a low diagnostic sensitivity of 20% with a maximum AUC of 0.59 and a CI of 0.300 to 0.870 without significant differences between the 3 available levels (L1, L2, L3). However, in processing of specimens presenting values >10% reactive or activated lymphocytes (x = 23%), typical for patients with infectious mononucleosis, the Var Lym flag showed a superior sensitivity of 75% with a diagnostic efficiency of 92% and an AUC of 0.84 with a CI of 0.587 to 1.089. Finally, the laboratory can easily program definitive abnormal morphological flags of distribution (granulocytosis, eosinophilia, monocytosis, and so forth) on the basis of its patient population. In this study we were able to carry out comparisons of AUC and to choose the values for the automated counts in percentage, absolute value, or both. Therefore we were able to define the reliability and impact on the alarm routine to optimize the performance of the user-adjustable definitive alarms for anomalous distribution.

Validation of the Coulter LH 750 in a hospital reference laboratory

Validation of the Coulter LH 750 was carried out in our central hospital laboratory, which processes 1500 hemograms per day for patients admitted into the 4 hospitals of our hospital complex and their corresponding outpatient departments. It is the reference laboratory for the provincial health care area. The analytical quality and the practical use of the instrument were studied, and we obtained within- and between-run imprecision estimates with reference controls of between 0.24% and 2.56% and inaccuracies of between -1.32% and 3.07% for basic hemogram parameters. Similar results were obtained with specimens from patients, with imprecision estimates between 0.56% and 2.56%. Linearity estimates were between 0.3 x 10(9)/L and 380 x 10(9)/L for leukocytes and between 3 x 10(9)/L and 1900 x 10(9)/L for platelets. The instrument evaluation was completed with a study of interference by bilirubin, lipemia, hemolysis, platelet clumps, and heparin and an examination of other variables, including carryover, detection limits, and the correlation of results with those of the Coulter Gen-S. A special evaluation was made of the new erythroblast count feature; with reference controls, imprecision estimates for this count were 10% to 12%, and with patient specimens imprecision averaged 10.39% up to 4 erythroblasts per 100 leukocytes. We also studied the correlation of LH 750 results and interferences with those of the manual reference method. Finally, National Committee for Clinical Laboratory Standards protocols were used to test for suspect and confirmation flags in leukocyte differential counts for 258 specimens representative of our routine. The practicability of the analyzer was studied in terms of technical difficulty, speed, and cost; also evaluated were new software elements for validation by source clinic and pathology and for reference values based on age. In conclusion, we analyzed the impact and improvements that may be expected in our laboratory (a user of Technicon and Coulter instruments) from introducing the new LH 750 analyzer into our routine.

Solution structure and proposed binding mechanism of a novel potassium channel toxin kappa-conotoxin PVIIA

BACKGROUND

kappa-PVIIA is a 27-residue polypeptide isolated from the venom of Conus purpurascens and is the first member of a new class of conotoxins that block potassium channels. By comparison to other ion channels of eukaryotic cell membranes, voltage-sensitive potassium channels are relatively simple and methodology has been developed for mapping their interactions with small-peptide toxins. PVIIA, therefore, is a valuable new probe of potassium channel structure. This study of the solution structure and mode of channel binding of PVIIA forms the basis for mapping the interacting residues at the conotoxin-ion channel interface.

RESULTS

The three-dimensional structure of PVIIA resembles the triple-stranded beta sheet/cystine-knot motif formed by a number of toxic and inhibitory peptides. Subtle structural differences, predominantly in loops 2 and 4, are observed between PVIIA and other conotoxins with similar structural frameworks, however. Electrophysiological binding data suggest that PVIIA blocks channel currents by binding in a voltage-sensitive manner to the external vestibule and occluding the pore. Comparison of the electrostatic surface of PVIIA with that of the well-characterised potassium channel blocker charybdotoxin suggests a likely binding orientation for PVIIA.

CONCLUSIONS

Although the structure of PVIIA is considerably different to that of the alphaK scorpion toxins, it has a similar mechanism of channel blockade. On the basis of a comparison of the structures of PVIIA and charybdotoxin, we suggest that Lys19 of PVIIA is the residue which is responsible for physically occluding the pore of the potassium channel.

Modal gating in neuronal and skeletal muscle ryanodine-sensitive Ca2+ release channels

The bursting behavior of ryanodine-sensitive single Ca2+ release channels present in chicken cerebellum endoplasmic reticulum (ER), rat hippocampus ER, and frog and rabbit skeletal muscle sarcoplasmic reticulum was established. Unconditional dwell time distributions fitted by the maximum likelihood method reveal at least three open and closed exponential components. Trains of low open probability (P(o)) bursts were interspersed with trains of high P(o) bursts (> or = 0.8) in all the ryanodine receptor isotypes tested. The gating kinetics of the Ca2+ release channels were defined in long recordings by analyzing burst sequences and gamma distributions of average intraburst open (T(o)) and closed times (Tc). The gamma distributions of T(o) had two gamma components, suggesting the existence of two distinct burst types. In contrast, the gamma distributions of Tc had only one component. The correlation between consecutive burst pairs was defined in terms of T(o) and then statistically tested by 2 x 2 matrix contingency analysis. The probability that the ubiquitous sequential burst pattern was generated by random occurrence was < 0.01 (two-tailed Fisher's exact test). Temporal correlations were observed in all ryanodine receptor isotypes under a variety of experimental conditions. These data strongly suggest that single Ca2+ release channels switch slowly between modes of gating. We propose that the effects of agonists of Ca2+ release channels such as Ca2+ itself can be explained as concentration-dependent changes in the availability of each mode.

A strongly interacting pair of residues on the contact surface of charybdotoxin and a Shaker K+ channel

Charybdotoxin, a peptide neurotoxin of known molecular structure, blocks Shaker K+ channels by binding to a receptor at the outer opening of the ion conduction pathway. Analysis of variants of CTX at position 29 and of Shaker at position 449 shows that these two residues interact closely in the channel-toxin complex. The CTX mutation M29I leads to a slight strengthening of block when tested on Shaker-449T; the same CTX mutation weakens block 1700-fold when tested on Shaker-449F. The known position of CTX-29 on the toxin's interaction surface thus locates Shaker-449 within 5 A of the pore axis of the closed channel. All four subunits must carry the 449F mutation to produce a highly toxin-insensitive channel.

Two subcellular mechanisms underlie calcium-dependent facilitation of bioluminescence

Epithelial calcium action potentials in Obelia geniculata trigger brief light flashes from specialized cells by direct activation of cytoplasmic calcium-activated photoprotein obelin. During a series of action potentials, sequential flashes undergo characteristic facilitation and decrement with no change in associated spike waveform. Analysis of the subcellular light distribution shows that facilitation results from two processes: recruitment of calcium entry sites and increased light from previously responding localized sites. We propose a model that accounts for the localized flash facilitation and decrement observed in vivo and is based upon the kinetics of calcium binding and emission of obelin. In this model, obelin emits light only when three calcium ions are bound. Changes in flash intensity during successive action potentials result from calcium bound persistently to unexpended obelin, effectively lowering the number of calcium ions required for subsequent activation. Accordingly, facilitation or decrement results from the time-dependent availability of singly and doubly bound obelin.

[The reduction of the ST segment during ergometry is not useful for the location of coronary stenosis]

We have analyzed 44 consecutive patients with significant ST-segment depression during the exercise stress test, with the aim of testing the ability of localizing the coronary stenoses. There was a significant correlation only between maximal ST-segment depression in V1-V4 and stenosis in the left anterior descending artery (r = 0.402, p = 0.0067), but the accuracy of the presence of ischemic ST depression in anterior leads to detect disease of the left anterior descending artery was 59% (26 correct, 18 wrong). The low lateral leads (V5 and V6) were the more accurate to detect coronary disease, as much for the left anterior descending artery as for the right or the circumflex coronary arteries. We conclude that ST segment depressions are of little value to localize the coronary stenoses.

A simple model for surface charge on ion channel proteins

We present a simple two-parameter model for surface charge directly associated with ion channels. A spherically symmetric "charged shell" models a distribution of surface charge arrayed about the channel entrance, with a corresponding set of image charges behind the plane of the membrane. The transition between a regime of buffered conductance and a regime of rapidly falling conductance at very low ionic strength is found to depend on the magnitude of the surface charge as well as the separation between the charge and the channel entrance. This resolves an apparent discrepancy between the experimental findings of Naranjo and Latorre (1993. Biophys. J. 64:1038-1050) and previous theoretical computations. The charged-shell model is used in a comparative study of the toad skeletal muscle conductance data of Naranjo and Latorre, the rat skeletal muscle conductances of Ravindran et al. (1992. Biophys. J. 61:494-508), and a second set of rat muscle conductances presented in this paper.

Modal shifts in acetylcholine receptor channel gating confer subunit-dependent desensitization

During the transition from embryonic to adult skeletal muscle, a decreased mean channel open time and accelerated desensitization of nicotinic acetylcholine (ACh) receptors result from the substitution of an epsilon subunit for gamma. A single ACh receptor channel of the embryonic type, expressed in Xenopus oocytes, interconverts between gating modes of short and long open time, whereas the adult receptor channel resides almost exclusively in the gating mode with short open time. Differences in the fraction of time spent in either gating mode account for the subunit dependence of both receptor open time and desensitization. Therefore, developmental changes in the kinetics of muscle ACh receptors may be imparted through subunit-dependent stabilization of intrinsic gating modes.

Ion conduction in substates of the batrachotoxin-modified Na+ channel from toad skeletal muscle

Batrachotoxin-modified Na+ channels from toad muscle were inserted into planar lipid bilayers composed of neutral phospholipids. Single-channel conductances were measured for [Na+] ranging between 0.4 mM and 3 M. When membrane preparations were made in the absence of protease inhibitors, two open conductance states were identified: a fully open state (16.6 pS in 200 mM symmetrical NaCl) and a substate that was 71% of the full conductance. The substate was predominant at [Na+] > 65 mM, whereas the presence of the fully open state was predominant at [Na+] < 15 mM. Addition of protease inhibitors during membrane preparation stabilized the fully open state over the full range of [Na+] studied. In symmetrical Na+ solutions and in biionic conditions, the ratio of amplitudes remained constant and the two open states exhibited the same permeability ratios of PLi/PNa and PCs/PNa. The current-voltage relations for both states showed inward rectification only at [Na+] < 10 mM, suggesting the presence of asymmetric negative charge densities at both channel entrances, with higher charge density in the external side. An energy barrier profile that includes double ion occupancy and asymmetric charge densities at the channel entrances was required to fit the conductance-[Na+] relations and to account for the rectification seen at low [Na+]. Energy barrier profiles differing only in the energy peaks can give account of the differences between both conductance states. Estimation of the surface charge density at the channel entrances is very dependent on the ion occupancy used and the range of [Na+] tested. Independent evidence for the existence of a charged external vestibule was obtained at low external [Na+] by identical reduction of the outward current induced by micromolar additions of Mg2+ and Ba2+.

[Prevalence of coronary disease in patients with aortic stenosis]

We analyzed a consecutive series of 188 patients, older than 44 years, with significant aortic stenosis, who underwent coronary arteriography (73 women and 115 men). There were 38 patients (20.2%) with coronary artery disease ( or = 50% reduction in the luminal diameter). Sixty-eight patients had typical angina pectoris, 52 atypical angina, and 68 did not have chest pain. We found to have coronary disease in 29.4%, 23.1% and 8.8% respectively. Sensitivity of typical angina to detect coronary disease was 52.6%, with an specificity of 68%, and a negative predictive value of 85%. Inclusion of atypical angina improved the sensitivity to 84.2%, and the negative predictive value to 91.2%, but lessened the specificity to 41.4%. Six patients among the 38 with coronary disease (15.7%), did not have chest pain, and 3 of them were younger than 60 years. We conclude that absence of angina is not enough to exclude coronary artery disease in patients 50 years old with aortic stenosis being considered for aortic valve replacement.