Prevalence and clinical profile of kidney disease in patients with chronic heart failure. Insights from the Spanish cardiorenal registry

INTRODUCTION AND OBJECTIVES

Patients with combined heart failure (HF) and chronic kidney disease (CKD) have been underrepresented in clinical trials. The prevalence of CKD in these patients and their clinical profile require constant evaluation. This study aimed to analyze the prevalence of CKD, its clinical profile, and patterns of use of evidence-based medical therapies in HF across CKD stages in a contemporary cohort of ambulatory patients with HF.

METHODS

From October 2021 to February 2022, the CARDIOREN registry included 1107 ambulatory HF patients from 13 HF clinics in Spain.

RESULTS

The median age was 75 years, 63% were male, and 48% had heart failure with reduced left ventricular ejection fraction (HFrEF). A total of 654 (59.1%) had an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2, and 122 (11%) patients with eGFR ≥ 60 mL/min/1.73 m2 had a urine albumin-creatinin ratio ≥ 30 mg/g. The most important variables associated with lower eGFR were age (R2=61%) and furosemide dose (R2=21%). The proportion of patients receiving an angiotensin-converting enzyme inhibitor (ACEI)/ angiotensin II receptor blockers (ARB), an angiotensin receptor-neprilysin inhibitor (ARNi), a sodium-glucose cotransporter 2 inhibitor (SGLT2i), or a mineralocorticoid receptor antagonist (MRA) progressively decreased with lower eGFR categories. Notably, 32% of the patients with HFrEF and an eGFR <30 mL/min/1.73 m2 received the combination of ACEI/ARB/ARNi+beta-blockers+MRA+SGLT2i.

CONCLUSIONS

In this contemporary HF registry, 70% of patients had kidney disease. Although this population is less likely to receive evidence-based therapies, structured and specialized follow-up approaches within HF clinics may facilitate the adoption of these life-saving drugs.

Sex differences in Cardiorenal Syndrome: Insights from CARDIOREN Registry

PURPOSE OF THE WORK

Although sex-specific differences in heart failure (HF) or kidney disease (KD) have been analyzed separately, the predominant cardiorenal phenotype by sex has not been described. This study aims to explore the sex-related differences in cardiorenal syndrome (CRS) in a contemporary cohort of outpatients with HF.

FINDINGS

An analysis of the Cardiorenal Spanish registry (CARDIOREN) was performed. CARDIOREN Registry is a prospective multicenter observational registry including 1107 chronic ambulatory HF patients (37% females) from 13 Spanish HF clinics. Estimated Glomerular Filtration Rate (eGFR) < 60 ml/min/1.73 m² was present in 59.1% of the overall HF population, being this prevalence higher in the female population (63.2% vs. 56.6%, p = 0.032, median age: 81 years old, IQR:74-86). Among those with kidney dysfunction, women displayed higher odds of showing HF with preserved ejection fraction (HFpEF) (odds ratio [OR] = 4.07; confidence interval [CI] 95%: 2.65-6.25, p < 0.001), prior valvular heart disease (OR = 1.76; CI 95%:1.13-2.75, p = 0.014), anemia (OR: 2.02; CI 95%:1.30-3.14, p = 0.002), more advanced kidney disease (OR for CKD stage 3: 1.81; CI 95%:1.04-3.13, p = 0.034; OR for CKD stage 4: 2.49, CI 95%:1.31-4.70, p = 0.004) and clinical features of congestion (OR:1.51; CI 95%: 1.02-2.25, p = 0.039). On the contrary, males with cardiorenal disease showed higher odds of presenting HF with reduced ejection fraction (HFrEF) (OR:3.13; CI 95%: 1.90-5.16, p < 0.005), ischemic cardiomyopathy (OR:2.17; CI 95%: 1.31-3.61, p = 0.003), hypertension (OR = 2.11; CI 95%:1.18-3.78, p = 0.009), atrial fibrillation (OR:1.71; CI 95%: 1.06-2.75, p = 0.025), and hyperkalemia (OR:2.43, CI 95%: 1.31-4.50, p = 0.005). In this contemporary registry of chronic ambulatory HF patients, we observed sex-related differences in patients with combined heart and kidney disease. The emerging cardiorenal phenotype characterized by advanced CKD, congestion, and HFpEF was predominantly observed in women, whereas HFrEF, ischemic etiology, hypertension, hyperkalemia, and atrial fibrillation were more frequently observed in men.

Hedgehog pathway and its inhibitors in chronic obstructive pulmonary disease (COPD)

COPD affects millions of people and is now ranked as the third leading cause of death worldwide. This largely untreatable chronic airway disease results in irreversible destruction of lung architecture. The small lung hypothesis is now supported by epidemiological, physiological and clinical studies. Accordingly, the early and severe COPD phenotype carries the most dreadful prognosis and finds its roots during lung growth. Pathophysiological mechanisms remain poorly understood and implicate individual susceptibility (genetics), a large part of environmental factors (viral infections, tobacco consumption, air pollution) and the combined effects of those triggers on gene expression. Genetic susceptibility is most likely involved as the disease is severe and starts early in life. The latter observation led to the identification of Mendelian inheritance via disease-causing variants of SERPINA1 - known as the basis for alpha-1 anti-trypsin deficiency, and TERT. In the last two decades multiple genome wide association studies (GWAS) identified many single nucleotide polymorphisms (SNPs) associated with COPD. High significance SNPs are located in 4q31 near HHIP which encodes an evolutionarily highly conserved physiological inhibitor of the Hedgehog signaling pathway (HH). HHIP is critical to several in utero developmental lung processes. It is also implicated in homeostasis, injury response, epithelial-mesenchymal transition and tumor resistance to apoptosis. A few studies have reported decreased HHIP RNA and protein levels in human adult COPD lungs. HHIP^+/- murine models led to emphysema. HH pathway inhibitors, such as vismodegib and sonidegib, are already validated in oncology, whereas other drugs have evidenced in vitro effects. Targeting the Hedgehog pathway could lead to a new therapeutic avenue in COPD. In this review, we focused on the early and severe COPD phenotype and the small lung hypothesis by exploring genetic susceptibility traits that are potentially treatable, thus summarizing promising therapeutics for the future.

Dose of furosemide before admission predicts diuretic efficiency and long-term prognosis in acute heart failure

AIMS

The outpatient diuretic dose is a marker of diuretic resistance and prognosis in chronic heart failure (HF). Still, the impact of the preadmission dose on diuretic efficiency (DE) and prognosis in acute HF is not fully known.

METHODS AND RESULTS

We conducted an observational and prospective study. All patients admitted for acute HF treated with intravenous diuretic and at least one criterion of congestion on admission were evaluated. Decongestion [physical examination, hemoconcentration, N-terminal pro-brain natriuretic peptide (NT-proBNP) change, and lung ultrasound], DE (weight loss and urine output per unit of 40 mg furosemide), and urinary sodium were monitored on the fifth day of admission. DE was dichotomized into high-low based on the median value. A multivariate Cox regression analysis was conducted to find predictors of HF readmission or mortality. A total of 105 patients were included between July 2017 and July 2019. Mean age was 74.5 ± 12.0 years, 64.8% were male, 33.3% had de novo HF, and mean left ventricular ejection fraction was 46 ± 17%. Median follow-up was 26 [15-35] months. Low DE based on weight loss was associated with a higher previous dose of furosemide (odds ratio [OR] 1.01 [1.00-1.02]), thiazide treatment before admission (OR 9.37 [2.19-40.14]), and lower diastolic blood pressure (OR 0.95 [0.91-0.98]) in the multivariate regression model. Only previous dose of furosemide (OR 1.01 [1.00-1.02]) and haemoglobin at admission (OR 0.76 [0.58-0.99]) were associated with low DE based on urine output in the multivariate analysis. The correlation between the previous dose of furosemide and DE based on weight loss was poor (r = -0.12; P = 0.209) and with DE based on urine output was weak to moderate (r = -0.33; P < 0.001). Low DE based on weight loss and urine output was associated with lesser decongestion measured by NT-proBNP (P = 0.011; P = 0.007), hemoconcentration (P = 0.006; P = 0.044), and lung ultrasound (P = 0.034; P = 0.029), but not by physical examination (P = 0.506; P = 0.560). Survival and event-free survival in acute decompensated HF (ADHF) were lower than in de novo HF; a preadmission dose of furosemide > 80 mg in ADHF identified patients with particularly poor prognosis (log-rank < 0.001). In ADHF, the preadmission dose of furosemide (hazard ratio [HR] 1.34 [1.08-1.67] per 40 mg) and NT-proBNP at admission (HR 1.03 [1.01-1.06] per 1000 pg/mL) were independently associated with mortality or HF readmission in the multivariate Cox regression analysis.

CONCLUSIONS

The outpatient dose of furosemide before acute HF admission predicts DE and must be taken into account when deciding on the initial diuretic dose. In ADHF, the outpatient dose of furosemide can predict long-term prognosis better than DE during hospitalization.

The development of chronic diuretic resistance can be predicted during a heart-failure hospitalization. Results from the REDIHF registry

Introduction

Diuretic resistance (DR) is a common condition during a heart failure (HF) hospitalization, and is related to worse prognosis. Although the risk factors for DR during a HF hospitalization are widely described, we do not know whether the risk of chronic DR could be predicted during admission.

Material and methods

We conducted a multicenter, prospective observational study between July 2017 and July 2019. All patients admitted for acute HF with intravenous diuretic treatment and at least one criterion of congestion on admission were invited to participate. Patients on renal replacement therapy, under intravenous diuretic treatment for >72 hours before screening and those who were unable to sign the informed consent were excluded. We monitored decongestion (physical exam, hemoconcentration, NTproBNP change and lung ultrasound) and DR (diuresis and weight loss per unit of 40mg furosemide and fractional excretion of sodium) on the fifth day of admission. Chronic DR was evaluate two months after hospitalization and was defined as persistent signs of congestion despite ≥80 mg furosemide per day. We compared variables from the hospitalization between patients with and without chronic DR. A multivariate logistic regression analysis was conducted to find predictors of chronic DR.

Results

A total of 105 patients were included in the study. Mean age was 74.5±12.0 years, 64.8% were male and mean LVEF was 46±17%. In the two months follow-up, five patients have died and one patient has had a heart transplant. Of the 99 remaining patients, 21 patients (21.2%) had chronic DR. The dose of furosemide before admission and the decrease in NT-proBNP ≤30% during admission were predictors of chronic DR in the multivariate analysis.

Conclusions

We can predict during a HF hospitalization which patients will develop chronic DR. The dose of furosemide before admission and the change in NT-proBNP are independent predictors of chronic DR.

P367 Cardioprotective effect of angiotensin converting enzyme inhibitors and beta-blockers in the primary prevention of cardiotoxicity: systematic review and meta-analysis of randomised studies

Funding Acknowledgements

none

OnBehalf

none

Background

Chemotherapy cardiotoxicity is a serious complication in breast and haematological malignancies. However, its primary prevention with angiotensin converting enzyme inhibitors (ACEI)/angiotensin II receptor antagonists (ARB) and/or beta-blockers (BB) medication has discrepant results. The aim of our study was to establish whether primary prevention using these treatments prevents cardiotoxicity and whether any of them is superior to the others.

Methods

A systematic review and meta-analysis was performed following a search of EMBASE, MEDLINE and PsycINFO from January 2005 to April 2019 of all randomised studies evaluating primary prevention of cardiotoxicity by chemotherapy with any of these treatments. Cardiotoxicity was defined as the drop of the left ventricular ejection fraction below 50% or greater than 10% and/or clinical heart failure during the first year of follow-up.

Results

Nine randomised studies with 913 participants in which chemotherapy was performed were included: 337 (37%) received BB, 152 (17%) received ACEI/ARB, 45 (5%) received BB + ACEI and 379 (41%) were controls. One hundred and eight cases (12%) developed cardiotoxicity (follow-up range: 1-12 months). Patients receiving cardioprotective treatment had a lower risk of developing cardiotoxicity than controls (RR = 0.381, IC95%, 0.160-0.911, P = 0.030, I2 = 63.2%; Fig.1). The subgroup analysis showed a non-significant tendency for both treatments to have a cardioprotective effect (BB: RR = 0.477; IC95%, 0.178-1.275; P = 0.140; I2 = 57.3%) / ACEI/ARB: RR = 0.283; IC95%, 0.027-2.982; P = 0.293; I2 = 79.0%). There was no difference between both treatments in those studies comparing them (RR = 0.743, CI95%, 0.325-1.698, P = 0.481, I2 = 0.0%). The estimated number of patients to be treated to avoid one case of cardiotoxicity was 10 patients.

Conclusions

Primary prevention with BB and/or ACEI/ARB reduces cardiotoxicity by chemotherapy during the first year in breast and haematological malignancies. For every 10 patients treated, one case of cardiotoxicity could be avoided.

Figure 1. Cases treated with BB and/or ACEI/ARB versus control group without treatment of the different randomised studies comparing the number of patients who developed cardiotoxicity during the first year.

Abstract P367 Figure 1

Influence of lane departure warnings onset and reliability on car drivers' behaviors

Lane departures represent an important cause of road crashes. The objective of the present study was to assess the effects of an auditory Lane Departure Warning System (LDWS) for partial and full lane departures (onset manipulation) combined with missed warnings (reliability manipulation: 100% reliable, 83% reliable and 66% reliable) on drivers' performances and acceptance. Several studies indicate that LDWS improves drivers' performances during lane departure episodes. However, little is known about the effects of the warning onset and reliability of LDWS. Results of studies which looked at forward collision warning systems show that early warnings tend to improve drivers' performances and receive a better trust judgement from the drivers when compared to later warnings. These studies also suggest that reliable assistances are more effective and trusted than unreliable ones. In the present study, lane departures were brought about by means of a distraction task whilst drivers simulated driving in a fixed-base simulator with or without an auditory LDWS. Results revealed steering behaviors improvements with LDWS. More effective recovery maneuvers were found with partial lane departure warnings than with full lane departure warnings and assistance unreliability did not impair significantly drivers' behaviors. Regarding missed lane departure episodes, drivers were found to react later and spend more time out of the driving lane when compared to properly warned lane departures, as if driving without assistance. Subjectively, LDWS did not reduce mental workload and partial lane departure warnings were judged more trustworthy than full lane departure ones. Data suggests the use of partial lane departure warnings when designing LDWS and that even unreliable LDWS may draw benefits compared to no assistance.

In vitro rescue of FGA deletion by lentiviral transduction of an afibrinogenemic patient's hepatocytes

BACKGROUND

Congenital afibrinogenemia is a rare inherited autosomal recessive disorder in which a mutation in one of three genes coding for the fibrinogen polypeptide chains Aα, Bβ and γ results in the absence of a functional coagulation protein. A patient with congenital afibrinogenemia, resulting from an FGA homozygous gene deletion, underwent an orthotopic liver transplant that resulted in complete restoration of normal hemostasis. The patient's explanted liver provided a unique opportunity to further investigate a potential novel treatment modality.

OBJECTIVE

To explore a targeted gene therapy approach for patients with congenital afibrinogenemia.

METHODS AND RESULTS

At the time of transplant, the patient's FGA-deficient hepatocytes were isolated and transduced with lentiviral vectors encoding the human fibrinogen Aα-chain. FGA-transduced hepatocytes produced fully functional fibrinogen in vitro.

CONCLUSIONS

Orthotopic liver transplantation is a possible rescue treatment for failure of on-demand fibrinogen replacement therapy. In addition, we provide evidence that hepatocytes homozygous for a large FGA deletion can be genetically modified to restore Aα-chain protein expression and secrete a functional fibrinogen hexamer.

Photophysical, amplified spontaneous emission and charge transport properties of oligofluorene derivatives in thin films

We investigate the charge transport, photophysical and amplified spontaneous emission properties of a series of monodisperse solution-processable oligofluorenes functionalized with hexyl chains at the C9 position of each fluorene unit.

[Molecular effects of new calcium antagonists: is the principle of parcimony out of place?]

The calcium (Ca2+) channel antagonists (CCA) are used successfully in the treatment of hypertension and angina pectoris. Their mode of action is to decrease Ca2+ entry in the vascular smooth muscle cells. Their molecular targets are voltage activated Ca2+ channels (VACC), especially the L-type (VACC-L). This review examines the role of the VACC-L and of the T-type (VACC-T) in vascular physiology and hypertension. The molecular mechanisms at the base of the vascular selectivity of CCA are presented with, in filigree, the concern of trying to understand the effect of recently developed molecules. In particular, we will examine the ideas having recently emerged concerning the mode of action of last generation dihydropyridines (DHPs) stripped of some of the undesirable effects of prototypes AC considered as highly specific of the VACC-L. These properties could result, in particular, from their effects on the VACC-T, which could occur in addition to those classically observed on the VACC-L.

Control of the refractive index in photopolymerizable materials for (2+1)D solitary wave guide formation

We report an experimental and theoretical study on the optimization of (2+1)D self-written waveguide formation inside a photopolymerizable material. The accurate control of the refractive index value inside the bulk of the material during the polymerization process gives us the opportunity to define a virtual core and a virtual cladding for the system. The V value which characterizes the guidance properties of a fiber can be applied to this propagation. The control of the V value allows us to propagate single mode or multimode waveguides on a few centimeters. Numerical simulations of these waveguides based on a paraxial model including both photopolymerization and Kerr effect give very good agreement with our experimental results.

Gap junction expression and cell proliferation in differentiating cultures of Cx43 KO mouse hepatocytes

Primary cultures of adult mouse hepatocytes are shown here to reexpress differentiated hepatocyte features following treatment with 2% DMSO and 10(-7) M glucagon. To examine the roles of gap junctional communication during hepatocyte growth and differentiation, we have compared treated and untreated hepatocytes from connexin (Cx)32-deficient [Cx32 knockout (KO)] and wild-type mice. In untreated cultures, DNA replication of Cx32 KO hepatocytes was markedly higher than of wild types. Although Cx26 mRNA levels remained high at all time points in wild-type and Cx32 KO hepatocytes, Cx32 mRNA and protein in wild-type hepatocytes underwent a marked decline, which recovered in 10-day treated cultures. Increased levels of Cx26 protein and junctional conductance were observed in Cx32 KO hepatocytes at 96 h in culture, a time when cell growth rate was high. Treatment with DMSO/glucagon highly reinduced Cx26 expression in Cx32 KO hepatocytes, and such treatment reinduced expression of both Cx32 and Cx26 expression in wild types. Dye transfer was not observed following Lucifer yellow injection into DMSO/glucagon-treated Cx32 KO hepatocytes, whereas the spread was extensive in wild types. Nevertheless, high junctional conductance values were observed in treated cells from both genotypes. These studies provide a method by which the differentiated phenotype can be obtained in cultured mouse hepatocytes and provide in vitro evidence that expression of gap junctions formed of Cx32 are involved in the regulation of growth of mouse hepatocytes.

Growth-suppressive function of human connexin32 in a conditional immortalized mouse hepatocyte cell line

Mouse hepatocytes immortalized with a temperature-sensitive allele of the SV40 large T-antigen (CHST8 cells) were found to lack the high expression of the gap junction proteins Cx26 and Cx32 that characterizes normal mouse hepatocytes, expressing instead Cx43 and Cx45 at minimal levels. In order to examine the growth suppressive function of Cx32 on hepatocytes, we transfected these CHST8 cells with human Cx32 complementary deoxyribonucleic acid and measured the growth rates at 33, 37, and 39 degrees C. Expression of human Cx32 and its messenger ribonucleic acid in the stable cell lines was confirmed by immunocytochemistry and by Western and Northern blots analyses. Dye transfer following lucifer yellow injection into the transfectants was extensive; Cx32 channels displayed unitary conductances of about 70 pS and were moderately voltage sensitive. When cultured at 33 and 39 degrees C, growth rates of both parental cells and transfectants were of the same level. When examined at 37 degrees C, growth rate of the transfectant, which highly expressed Cx32 at the membranes, was significantly decreased compared to the parental cells. However, no changes in the expression of Cx32 protein in the transfectants were observed between 33 and 37 degrees C. These results suggest that Cx32 expression could inhibit hepatocyte growth in vitro using the conditional immortalized cells. Cx32 transfectants using a conditional immortalized mouse hepatocyte may be useful for examining the mechanisms of growth and differentiation in hepatocytes by gap junction expression.

Olfactory learning induces differential long-lasting changes in rat central olfactory pathways

In the present work, we investigated lasting changes induced by olfactory learning at different levels of the olfactory pathways. For this, evoked field potentials induced by electrical stimulation of the olfactory bulb were recorded simultaneously in the anterior piriform cortex, the posterior piriform cortex, the lateral entorhinal cortex and the dentate gyrus. The amplitude of the evoked field potential's main component was measured in each site before, immediately after, and 20 days after completion of associative learning. Evoked field potential recordings were carried out under two experimental conditions in the same animals: awake and anesthetized. In the learning task, rats were trained to associate electrical stimulation of one olfactory bulb electrode with the delivery of sucrose (positive reward), and stimulation of a second olfactory bulb electrode with the delivery of quinine (negative reward). In this way, stimulation of the same olfactory bulb electrodes used for inducing field potentials served as a discriminative cue in the learning paradigm. The data showed that positively reinforced learning resulted in a lasting increase in evoked field potential amplitude restricted to posterior piriform cortex and lateral entorhinal cortex. In contrast, negatively reinforced learning was mainly accompanied by a decrease in evoked field potential amplitude in the dentate gyrus. Moreover, the expression of these learning-related changes occurred to be modulated by the animals arousal state. Indeed, the comparison between anesthetized versus awake animals showed that although globally similar, the changes were expressed earlier with respect to learning, under anesthesia than in the awake state. From these data we suggest that associative olfactory learning involves different neural circuits depending on the acquired value of the stimulus. Furthermore, they show the existence of a functional dissociation between anterior and posterior piriform cortex in mnesic processes, and stress the importance of the animal's arousal state on the expression of learning-induced plasticity.

A real-time two-dimensional pulsed-wave Doppler system

An experimental system was developed to acquire and visualise in real-time two-dimensional (2-D) velocity maps. Data acquisition is performed by using a modified commercial echograph based on a 5-MHz, 128-element linear-array transducer with electronic focussing and beam steering. Additional electronics were integrated into the echograph to implement a 2-D Doppler system capable of measuring the velocity component on the scanning plane. Suitable axial and lateral scanning methods were studied to obtain Doppler measurements over a scanning area. A colour image of the estimated velocity field is presented in real time on a personal computer using different visualisation techniques. The system performance was tested experimentally both in vitro and in vivo on a human carotid artery.

Neurophysiological mechanisms of auditory selective attention in humans

This chapter reviews the main data on the physiological substrates of auditory selective attention and their contribution to theoretical models of cognitive psychology. While event-related potentials, magnetoencephalography, and more recently neuroimaging techniques have provided fundamental information on the neural correlates of attention in the central cortical system, measurements of the frequency-following responses in the brainstem and evoked otoacoustic emissions at the cochlea strongly suggest attentional phenomena at the auditory periphery. We propose an adaptive filtering mechanism for selective auditory attention that can be flexibly and dynamically tuned depending on the attentional demand.

TPA induced expression and function of human connexin 26 by post-translational mechanisms in stably transfected neuroblastoma cells

Connexin 26 (Cx26) has been proposed to be a tumor suppressor gene and its expression may modulate development, cell growth and differentiation in various tissues, including the brain. 12-O-tetradecanoylphorbol-13-acetate (TPA) may serve as either tumor promoter (in mammary gland amd skin) or as a differentiating agent (in neuroblastoma and leukemic cells) and may also modulate expression, function and phosphorylation of gap junctions. In this study, to determine the effects of TPA on Cx26 expression and its function in neuroblastoma, we transfected N2A mouse neuroblastoma cells (which are gap junction deficient) with the coding region of human Cx26 gene (which lacks TPA response elements) and examined the changes of expression and function of Cx26 following 10 nM TPA treatment. Individual clones of transfectants stably expressed distinct levels of exogenous Cx26 as judged by Northern and Western blots, immunocytochemistry and electrophysiological recordings. Cx26 channels displayed unitary conductances of about 140-155 pS. Increase of Cx26 expression following TPA treatment was markedly observed using immunocytochemistry and Western blots of membrane fractions although it was not detected in Northern or Western blots of whole cells. This increase in Cx26 expression in the plasma membrane was accompanied by an increase of function as evidenced in measurements of junctional conductance. These results suggest that induction of exogenous Cx26 in neuroblastoma cells by TPA treatment is controlled by post-translational mechanisms.

Voltage dependence of macroscopic and unitary currents of gap junction channels formed by mouse connexin50 expressed in rat neuroblastoma cells

1. The macroscopic and single channel gating characteristics of connexin (Cx) 50 gap junction channels between pairs of N2A neuroblastoma cells transfected with mouse Cx50 DNA were investigated using the dual whole-cell voltage clamp technique. 2. The macroscopic junctional current (Ij) of Cx50-transfected cells decayed exponentially with time in response to transjunctional voltage (Vj) steps (time constant (tau) of approximately 4 s at a Vj of 30-40 mV and 100-200 ms at a Vj of 80-100 mV). The steady-state junctional conductance (gj) was well described by a two-state Boltzmann equation. The half-inactivation voltage (V0), the ratio of minimal to maximal gj (gmin/gmax) and the equivalent gating charge were +/- 37 mV, 0.21 and 4, respectively. 3. The conductance of single Cx50 channels measured using patch pipettes containing 130 mM CsCl was 220 +/- 13.1 pS (12 cell pairs). A prominent residual or subconductance state corresponding to 43 +/- 4. 2 pS (10 cell pairs) was also observed at large Vj s. 4. The relationship between channel open probability (Po) and Vj was well described by a Boltzmann relationship with parameters similar to those obtained for macroscopic gj (V0 = 34 mV, gating charge = 4.25, maximum P= 0.98). The ensemble average of single channel currents at Vj = 50 mV declined in a monoexponential manner (tau = 905 ms), a value similar to the decline of the macroscopic Ij of Cx50 channels at the same voltage. 5. Ion substitution experiments indicated that Cx50 channels have a lower permeability to anions than to cations (transjunctional conductance of KCl vs. potassium glutamate (gammaj, KCl/gammaj,KGlut), 1.2; 6 cell pairs). 6. The results have important implications for understanding the role of connexins in tissues where Cx50 is a major gap junction component, including the lens.

A 3-D PW ultrasonic Doppler flowmeter: theory and experimental characterization

A complete 3-D ultrasonic pulsed Doppler system has been developed to measure quantitatively the velocity vector field of a fluid flow independently of the probe position. The probe consists of four 2.5 MHz piezocomposite ultrasonic transducers (one central transmitter and three receivers separated by 120 degrees ) to measure the velocity projections along three different directions. The Doppler shift of the three channels is calculated by analog phase and quadrature demodulation, then digitally processed to extract the mean velocity from the complex spectrum. The accuracy of the 3-D Doppler technique has been tested on a moving string phantom providing an error of about 4% for both amplitude and direction with an acquisition window of 100 ms.

Acoustic analysis of newborn infant cry signals

This paper aims at estimating the fundamental frequency (pitch) and the vocal tract resonant frequencies (formants) from newborn infant cry signals. Such parameters are of interest in exploring brain function at early stages of child development, for the timely diagnosis of neonatal disease and malformation. The paper compares a spectral parametric technique and the cepstrum approach, extending previous results. The parametric technique is based on autoregressive models whose order is adaptively estimated on subsequent signal frames by means of a new method. This allows the correct tracking of pitch and formant variations with time. The traditional cepstrum approach is modified in order to follow signal variability. In particular, the cepstrum spectral resolution is improved by applying the chirp Z-transform (CZT) and by adaptively varying the 'lifter' length. The two methods are tested on simulated data, as far as robustness to noise and spectral resolution are concerned, and are then applied to real baby cry data.

Recursive autoregressive spectral maps for ocular pathology detection

This article presents a new approach to the problem of obtaining topological maps for tissue characterization, based on spectral parameters extracted from radio frequency (RF) backscattered ultrasonic signals. The spectral parameter we deal with is the power spectral density centroid, since it is an efficient indicator of the tissue microstructure characteristics as far as the particle dimensions are concerned. The spectral analysis of RF ultrasonic echoes is performed using a recursive least-squares scheme with a variable forgetting factor, based on low-order autoregressive models. The proposed technique is particularly tailored to the differentiation of ocular pathologies; moreover, it is capable of tracking the spatial high-varying signal characteristics. The proposed approach was tested on simulated signals and on a gel suspension of calibrated latex spheres; finally, it was applied to signals scattered by in vitro eye specimens, giving satisfactory results in terms of frequency resolution and computational efficiency. The reduced computational burden allows an on-line implementation of the procedure. Topological spectral maps, combined with the conventional B-mode display, may offer a complete and integrated diagnostic tool, able to locally characterize the investigated tissue region in terms of amplitude and frequency shift of the corresponding echoes.

Towards equity in long-term care

There are considerable similarities and overlap in the levels of disability and dependency between those who receive home-based-long-term care and those who receive long-term care on a residential basis. These similarities are demonstrated from analysis of clients of the Western Domiciliary Care and Rehabilitation Service. When services are costed, it is shown that there is a very large discrepancy in the levels of government support that clients of home-based care agencies attract compared to residents in subsidised hostels and nursing homes. This paper discusses the need for parity of funding to care providers and recognition of the economic value of the contributions of carers. It considers principles for the development of a casemix model for home-based care analogous to the Care Aggregated Module/Standard Aggregated Module (CAM)/(SAM) model applying to nursing home care.

Parametric and non-parametric estimation of speech formants: application to infant cry

The present paper addresses the issue of correctly estimating the peaks in the speech envelope (formants) occurring in newborn infant cry. Clinical studies have shown that the analysis of such spectral characteristics is a helpful noninvasive diagnostic tool. In fact it can be applied to explore brain function at very early stage of child development, for a timely diagnosis of neonatal disease and malformation. The paper focuses on the performance comparison between some classical parametric and non-parametric estimation techniques particularly well suited for the present application, specifically the LP, ARX and cepstrum approaches. It is shown that, if the model order is correctly chosen, parametric methods are in general more reliable and robust against noise, but exhibit a less uniform behaviour than cepstrum. The methods are compared also in terms of tracking capability, since the signals under study are nonstationary. Both simulated and real signals are used in order to outline the relevant features of the proposed approaches.

Adaptive SVD-based AR model order determination for time-frequency analysis of Doppler ultrasound signals

The short-time Fourier transform provides a picture of the spectral components temporal location in time-varying signals, but its performance is limited by the intrinsic trade-off between time and frequency resolutions. In the present study, this problem is addressed using a spectral estimator based on a combination of the autoregressive (AR) modeling technique and a new automatic model order selection method. The order estimation is achieved by means of the singular value decomposition (SVD) of an appropriate data matrix in conjunction with a new criterion (dynamic mean evaluation, DME). The latter is used to decide which singular values correspond to the signal and which to the noise subspaces, avoiding an a priori threshold definition, thus giving the variable AR model order on consecutive short-time segments. Combination of the AR high frequency resolution capabilities and the SVD plus DME robustness and simplicity make the overall method reliable in many practical applications, mainly in the analysis of time-varying signals corrupted by noise. The proposed procedure has been applied to benchmark as well as to Doppler signal analysis. Some examples are reported confirming the above-mentioned properties.

Non-conventional ultrasonography (power spectrum analysis) in the management of retinoblastoma

The differential diagnosis among the diseases that may simulate retinoblastoma is supported by several techniques; however, none of them can give an undeniable answer. In the authors' opinion the tissue characterization by power spectrum analysis of the radiofrequency ultrasound data may play an important role in the backscattered signal spectrum while being sensitive to the spectral shift trend. In order to evaluate the patterns of regression of quiescence of retinoblastoma foci after conservative treatment the authors try to create a model of tissue characterization that provides information not available in conventional A & B scan ultrasonography about cell type, vascularization and necrosis.