Profilin Isoforms in Health and Disease - All the Same but Different

Profilins are small actin binding proteins, which are structurally conserved throughout evolution. They are probably best known to promote and direct actin polymerization. However, they also participate in numerous cell biological processes beyond the roles typically ascribed to the actin cytoskeleton. Moreover, most complex organisms express several profilin isoforms. Their cellular functions are far from being understood, whereas a growing number of publications indicate that profilin isoforms are involved in the pathogenesis of various diseases. In this review, we will provide an overview of the profilin family and "typical" profilin properties including the control of actin dynamics. We will then discuss the profilin isoforms of higher animals in detail. In terms of cellular functions, we will focus on the role of Profilin 1 (PFN1) and Profilin 2a (PFN2a), which are co-expressed in the central nervous system. Finally, we will discuss recent findings that link PFN1 and PFN2a to neurological diseases, such as amyotrophic lateral sclerosis (ALS), Fragile X syndrome (FXS), Huntington's disease and spinal muscular atrophy (SMA).

Drebrin controls scar formation and astrocyte reactivity upon traumatic brain injury by regulating membrane trafficking

The brain of mammals lacks a significant ability to regenerate neurons and is thus particularly vulnerable. To protect the brain from injury and disease, damage control by astrocytes through astrogliosis and scar formation is vital. Here, we show that brain injury in mice triggers an immediate upregulation of the actin-binding protein Drebrin (DBN) in astrocytes, which is essential for scar formation and maintenance of astrocyte reactivity. In turn, DBN loss leads to defective astrocyte scar formation and excessive neurodegeneration following brain injuries. At the cellular level, we show that DBN switches actin homeostasis from ARP2/3-dependent arrays to microtubule-compatible scaffolds, facilitating the formation of RAB8-positive membrane tubules. This injury-specific RAB8 membrane compartment serves as hub for the trafficking of surface proteins involved in astrogliosis and adhesion mediators, such as β1-integrin. Our work shows that DBN-mediated membrane trafficking in astrocytes is an important neuroprotective mechanism following traumatic brain injury in mice.

Contrast induced acute kidney injury prevention during angiographic procedure with early renal replacement therapy

Background and purpose

Post-angiography renal replacement therapy (RRT) has shown protective effects from Ci-AKI (contrast induced acute kidney injury) in patients with pre-existing advanced renal disfunction. We analysed a series of 1095 continuative patients who undergone coronary or peripheral angiography in our center. In non-haemodialyzed patients with eGFR <20ml/min/1.73m2 or with poor renal reserve we performed an “early” RRT, starting during angiography procedure and applied for at least 6 h after procedure, thus diverging from previous literature data based only on post-procedure hours delayed RRT application. The RRT modality chosen was CVVHDF (continous veno-venous hemodiafiltration).

Methods

We considered following subjects variability: age, sex, weight, presence of hypertension, dyslipidaemia, diabetes, smoking habitude, left ventricular ejection fraction, amount of contrast media given and shock or infection occurrence during hospital stay. We evaluate statistic significative of serum creatine (SCr) variation in patients receiving RRT from pre-procedure time (T0), at 24h (T1), 48h (T2), 72h (T3) after procedure and at 3–8 weeks follow-up (T4). Quantitative data were compared with Student T test, qualitative data with Chi Square test, considering statistically significant p value <0.05 with two tails. Ci-AKI was defined as serum creatinine rise ≥0.3 mg/dL at 48h from contrast media administration, following KDIGO (kidney disease improving global outcomes) guidelines definition.

Results

26 patients received RRT. Medium SCr at T0 was 3.37 mg/dl and showed a significative reduction (see figure) at T1 (−0.88mg/dl = −20.6%, p=0.003) and T2 (−0.96mg/dl = −18.33%, p=0.029) and a trend towards reduction at T3 (−0.78mg/dl, p=0.174) and at T4 (−0.28mg/dl, p=0.568).

Between 26 pts, 6 pts (23%) developed Ci-AKI. Only contrast media amount significatively diverge between two groups (183 ml in the group with Ci-AKI vs 162 ml in pts with no Ci-AKI, p=0.03), showing also a trend towards significance for infection occurrence (83.3% pts Ci-AKI vs 40% pts no Ci-AKI, p=0.06) and shock onset (33.3%pts Ci-AKI vs 5% pts no Ci-AKI, p=0.06).

Average SCr diverge at T2 (3.18mg/dl Ci-AKI vs 2.04mg/dl no Ci-AKI, p=0.01) and at T3 (3.33mg/dl CI-AKI vs 2.31mg/dl no CI-AKI, p=0.06); we also found a trend towards progressive increase of SCr for Ci-AKI pts (T0-T1: +0.17mg/dl, p=ns; T0-T2: +0.41mg/dl, p=ns; T0-T3: +0.57mg/dl, p=ns; T0-T4: +1.35mg/dl, p=ns) and a significative reduction in SCr for no Ci-AKI pts (T0-T1: −1.23mg/dl = −29.32% p=0.001; T0-T2: −1.46mg/dl = −30.78%, p=0.01; T0-T4: −0.41mg/dl = −15.5%, p=0.05).

Conclusions

Early RRT with CVVHDF modality results effective in 77% of patients in avoiding Ci-AKI, with a significative SCr reduction at 24 and 48h. An increased amount of contrast media is significatively related to Ci-AKI incidence. Ci-AKI development could also possibly be related to shock and infection occurrence.

Figure 1

Funding Acknowledgement

Type of funding source: None

Impact of perioperative haemodynamic monitoring on cardiac morbidity after major vascular surgery in low risk patients. A randomised pilot trial

OBJECTIVE

to evaluate whether perioperative haemodynamic optimisation influences outcome from infrarenal abdominal aortic aneurysm repair.

METHODS

a consecutive series of 100 eligible patients were randomised to either haemodynamic optimisation through the use of a pulmonary artery catheter (CI > 3.0 l/min/sqm, PWP > 10 and <18 mmHg, SVR <1450 dyne/sec/cm(-5), DO(2)> 600 ml/min/sqm) or conventional treatment.

RESULTS

there were no differences in terms of in-hospital mortality, cardiovascular morbidity, postoperative renal failure or duration of hospital stay between the groups.

CONCLUSIONS

in this study perioperative haemodynamic optimisation was not beneficial.

Left ventricular opacification by intravenous contrast echocardiography

BACKGROUND

The present study was undertaken in order to evaluate the efficacy of the intravenous administration of Albunex in obtaining left ventricular opacification and the relationship between left ventricular opacification and pulmonary pressures and cardiac function.

METHODS

Fifty-two adult patients, mostly affected by ischemic heart disease, were enrolled in the study. In 37 of these patients, a complete right heart hemodynamic study was performed after Swan-Ganz catheterization. Albunex was administered in three randomized doses (0.10, 0.15 and 0.20 ml/kg) to all the patients. Left ventricular opacification was assessed both visually and using videodensitometric analysis.

RESULTS

Left ventricular opacification was obtained in 93% of all the injections and an intermediate or strong opacification was obtained in 68%, while absent opacification was observed in 6% of the injections, irrespective of the contrast dose. An incremental opacification efficacy trend was observed from the lower to the higher dose, with an intermediate or strong opacification in 58 and in 77% of 0.10 and 0.20 ml/kg injections, respectively. Irrespective of the contrast dose, an enhancement of the endocardial borders was observed in 61% of the wall segments suboptimally visualized in basal conditions. The endocardial borders enhancement was obtained in 39 and in 79% of segments using the 0.10 and the 0.20 ml/kg doses, respectively. No statistically significant differences were observed between the videodensitometric parameters obtained using the three contrast doses. Finally, a significant relationship was observed between left ventricular opacification parameters and pulmonary pressures and left ventricular functional parameters, irrespective of the contrast doses considered.

CONCLUSIONS

The results we obtained demonstrate the good overall efficacy of Albunex administered intravenously in order to obtain left ventricular opacification in a clinical population of cardiac patients. Moreover, they suggest that the dosage to be used clinically should preferably be at least 0.20 ml/kg, although no significant influence of contrast dosage on videodensitometric parameters has been observed. Finally, irrespective of the contrast dosage, the magnitude of left ventricular opacification appears to be influenced by the hemodynamic status of the patient.

Effect of sample volume location on Doppler-derived transmitral inflow velocity values in 288 normal subjects 20 to 80 years old: an echocardiographic, two-dimensional color Doppler cooperative study

The aims of the study were to evaluate in a population of 288 normal subjects 20 to 80 years old (1) the normal values of the indexes of the mitral flow velocity pattern measured either at the tips of the mitral leaflets or at the annulus; (2) whether there was a significant difference between the values obtained at the tips compared with those measured at the mitral annulus; (3) the correlation with aging between the indexes measured in the two different positions; and (4) whether certain physiological variables have different effects on diastolic function measured in the two different positions. The highest values were always measured at the tips of the mitral leaflets (p < 0.05); only atrial filling fraction, E acceleration time, and E deceleration velocity had higher values when measured at the level of the annulus (p < 0.05). The A-wave peak velocity had the same mean value when measured at both the tips and at the annulus. A significant difference in the correlation between parameters measured at the tips of the mitral leaflets with age and at the annulus (with age) was observed for the following parameters: (1) peak E velocity, E integral, total integral and E acceleration showed better correlation with age when measured at the annulus (p < 0.02); (2) peak A velocity and A integral showed better correlation with age when measured at the tips of the mitral leaflets (p < 0.001). Multivariate analysis showed that age was the variable that had the most influence on diastolic function parameters; heart rate had less influence on the diastolic function indexes.

Pulmonary venous flow velocity patterns in 143 normal subjects aged 20 to 80 years old. An echo 2D colour Doppler cooperative study

In order to find out the normal values and to evaluate the effects of age, heart rate, sex, and haemodynamic and standard echocardiographic parameters on pulmonary venous flow velocity obtained by the transthoracic approach. Doppler pulmonary venous flow parameters were measured in 143 healthy subjects aged from 20 to 80 years. Doppler pulmonary venous flow parameters which had the best correlation with age were: the peak velocity of the systolic wave (r = 0.39) and its integral (r = 0.5), the peak velocity of the diastolic wave (r = -0.6) and its integral (r = -0.44); the systolic (r = 0.68) and diastolic fractions (r = -0.68); the systolic/diastolic peak velocity ratio (r = 0.73) and the systolic/diastolic integral ratio (r = 0.7). The atrial reversal wave did not correlate with age; the atrial reversal wave was more difficult and probably less reliable to measure than the systolic and diastolic waves. The correlations of pulmonary venous flow parameters with mitral flow parameters were also examined. This study showed that, in healthy subjects, despite an increase in the early and atrial waves from the annulus to the tips of the mitral leaflets, there is a similar association between pulmonary venous flow and mitral flow measured at the annulus or at the tips of the mitral leaflets. The intra-observer reproducibility of all the pulmonary venous flow parameters considered were found to be excellent. Moderate inter-observer variability was observed for the systolic, diastolic and atrial reversal wave peak velocities and integrals; however, the systolic/diastolic ratio improved the precision of the measurements. Multivariate analysis showed that age is the principal determinant of the Doppler parameters of pulmonary venous flow: heart rate, sex, body surface area, the size of the left atrium in systole and the left ventricular ejection fraction all influence the Doppler parameters of pulmonary venous flow, even if only slightly.

Demonstration of the relationship between heart dimensions and QRS voltage amplitude

This study was undertaken to elucidate the still debated question of the relationship between cardiac volume and QRS voltage amplitude. The authors studied 14 healthy men, aged 24-61 years (mean age, 41.2 +/- 12.1 years). They underwent a reduction in venous return, produced by simultaneously inflating sphygmomanometric cuffs placed around the most proximal portion of each of the four limbs. In basal conditions and 5 minutes after cuff inflation, two-dimensional and M-mode echocardiograms were recorded with vectorcardiographic loops and scalar Frank leads. The reduction of the venous return to the heart induced a significant decrease of the end-diastolic left ventricular diameter (from 52.4 +/- 4.2 to 48.5 +/- 4.6 mm, P < .001), of the R wave amplitude in leads X and Y, of the sum of the R wave amplitudes in the three leads,and of the maximal vector in the frontal and horizontal planes. No significant changes in the heart rate or arterial blood pressure were observed. These results support Brody's theory concerning the relationship between cardiac blood volume and QRS voltage.

Dobutamine echocardiography: usefulness of digital image processing

The present study was undertaken in order specifically to evaluate the usefulness of digital image processing so as to enhance the diagnostic power of dobutamine stress echocardiography. For this purpose 44 dobutamine echocardiographic tests, routinely performed in our echo laboratory, were analysed blindly by two observers using traditional videotape recording and digitized image acquisition. The results obtained from both observers show a trend which suggests that the traditional videotape approach provides more true-positive tests than the digitized approach (27/38 vs 23/38 and 24/38 vs 22/38 for the first and second observer, respectively). True-negative test detection was 6/6 with the videotape and 5/6 with the digitized method for both observers. As a consequence of the discrepancies observed between the two modalities, the videotape indicates that it can provide higher diagnostic accuracy than the digitized approach (72 +/- 9% vs 63 +/- 10%). The tests results concordance (positive or negative) between the two modalities of analysis was 66% for both the observers. The inter-observer agreement on the test results was 84% and 80% for the videotape analysis and the digitized analysis, respectively. On the basis of the results, we consider that digitized analysis applied to dobutamine stress echocardiography does not afford significant diagnostic advantages and should not be considered as an alternative option to traditional videotape analysis. However, it may be considered an extremely useful integrative tool since it produces the on-line image evaluation more easily and faster and allows a more practical form of stress test storage.

[Coronary vasospasm secondary to subcutaneous administration of sumatriptan]

We present the case of a 38-year-old woman with no previous history of coronary heart diseases, who suffered from cluster headaches and had undergone a subcutaneous sumatriptan treatment for two years. With no previous history of underlying ischaemic heart diseases or Prinzmetal's angina or any other significant coronary diseases supported by an angiographic exam, the patient suffered from an episode of coronary vasospasm following a subcutaneous administration of sumatriptan. Therefore particular care should be placed when subcutaneous sumatriptan is administered to patients who experienced chest pain or other related symptoms after the use of the drug.

["Incomplete closure" of the mitral valve: the relationships to valvular regurgitation and to the morphofunctional characteristics of the left ventricle]

OBJECTIVES

The present study was designed in order to evaluate the prevalence of mitral regurgitation in patients with the "incomplete mitral leaflet closure" echocardiographic pattern, to verify whether the amount of "incomplete mitral leaflet closure" is related to the severity of mitral regurgitation and, last, to verify the relation between the "incomplete mitral leaflet closure" and left ventricular morphology and function.

METHODS

We studied 80 patients (14 patients with dilatative cardiomyopathy, 26 patients with coronary artery disease, and 40 patients with hypertensive heart disease or aortic valve disease) showing the "incomplete mitral leaflet closure" pattern, retrospectively selected from a population composed of 1700 consecutive patients routinely examined in our echocardiographic laboratory. In all patients we evaluated the presence and the severity of mitral regurgitation, the morphological and functional parameters of the left ventricle, the systolic diameter of the mitral annulus, the distance between the point of mitral leaflet coaptation and the annular plane, and the incomplete mitral closure area, assuming the last two parameters as indexes of the severity of incomplete closure of the mitral valve.

RESULTS

We observed the presence of mitral regurgitation in 51 out of 80 patients (64%). The valvular insufficiency was considered mild in 78% of the patients. We observed no significant difference between patients with mitral regurgitation and without, as regards the diameter of the mitral annulus, the distance between the point of mitral leaflet coaptation and the annular plane, and the incomplete mitral closure area in different types of heart diseases. The incomplete mitral closure area and the diameter of the mitral annulus showed a significant, although not elevated, correlation with the severity of the mitral regurgitation (r = 0.36 and r = 0.32, respectively). The severity of mitral regurgitation showed significant correlations with all of the left ventricular morphological and functional parameters evaluated. Finally, we observed significant correlations between the incomplete mitral closure area and all of the morphological and functional parameters of the left ventricle.

CONCLUSIONS

On the basis of the results obtained we can conclude that: 1) the "incomplete mitral leaflet closure" pattern does not appear to be a highly specific marker of mitral regurgitation, 2) this pattern appears to be related to the morphology and function of the left ventricle, and 3) the severity of the incomplete mitral valve closure is more easily evaluated by a parameter that takes into account the numerous factors acting on the mitral apparatus, that is the incomplete mitral closure area.

Effects of preload reduction on mitral flow velocity pattern in normal subjects

In the last few years, alterations in transmitral diastolic flow pattern have been used to assess changes in left ventricular diastolic properties. However, since diastolic flow primarily reflects the atrioventricular pressure gradient, loading conditions, as well as intrinsic left ventricular properties, should be able to affect this pattern. This study was selectively designed to decrease preload (a major determinant of the atrioventricular pressure gradient) in normal subjects to observe the effects on the Doppler transmitral flow pattern without pharmacologic interventions that may also affect left ventricular diastolic properties. In 12 normal subjects, preload was reduced by inflation of blood pressure cuffs placed at the level of the root of the 4 limbs. The peak velocity of early mitral flow (E wave) decreased from 62 +/- 8 to 51 +/- 7 cm/s (p less than 0.001), while no changes were found in the maximal velocity after atrial contraction; this caused a significant decrease in the ratio of these 2 velocities (the E to A ratio) from 1.5 +/- 0.3 to 1.1 +/- 0.1 (p less than 0.001). The time-velocity integral of early diastolic inflow decreased from 7.8 +/- 1.3 to 6.1 +/- 1.3 cm (p less than 0.001) with no significant changes of the time-velocity integral of inflow after atrial contraction. Therefore, preload reduction in normal subjects significantly reduces transmitral flow in early diastole with preserved late ventricular filling, producing a pattern that can mimic the changes previously described in left ventricular diastolic dysfunction.

[A comparison between mitral and aortic outputs evaluated by Doppler echocardiography in a group of healthy subjects: false regurgitation]

Doppler echocardiography is a potentially useful tool for the non invasive evaluation of cardiac output and, therefore, for the quantitative assessment of valvular regurgitation. The aim of our study was to establish the presence of possible pitfalls in the evaluation of mitral and aortic regurgitant fraction obtained by Doppler echocardiography comparing the cardiac output measured at the level of the mitral and aortic valve. For this purpose 19 healthy volunteers, aged between 14-68 years, were studied. Stroke volume and cardiac output were calculated at the level of the mitral and aortic valve. The methods we used for the measurement of both the mitral and aortic cardiac output had already been validated and presumes that the shape of the valve annulus, is circular. No statistically significant differences were found between the parameters obtained at the two different valvular levels. Furthermore, cardiac output values correlated fairly well (r = 0.83, ESS = 0.78 l/min). In 9 subjects the aortic cardiac output was greater than the mitral one, while in the others mitral cardiac output was greater. The average of the differences between the two cardiac outputs was 0.58 +/- 0.48 l/min with a regurgitation fraction of 9.5 +/- 7.9%. Our results show that the mitral and aortic stroke volume and cardiac output, as measured by Doppler echocardiography (considering a circular shaped valve annulus, are not statistically different and correlate fairly well in our normal subjects. Nevertheless, we observed a certain degree of variability between the mitral and the aortic cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)