Highly efficient platelet generation in lung vasculature reproduced by microfluidics

Platelets, small hemostatic blood cells, are derived from megakaryocytes. Both bone marrow and lung are principal sites of thrombopoiesis although underlying mechanisms remain unclear. Outside the body, however, our ability to generate large number of functional platelets is poor. Here we show that perfusion of megakaryocytes ex vivo through the mouse lung vasculature generates substantial platelet numbers, up to 3000 per megakaryocyte. Despite their large size, megakaryocytes are able repeatedly to passage through the lung vasculature, leading to enucleation and subsequent platelet generation intravascularly. Using ex vivo lung and an in vitro microfluidic chamber we determine how oxygenation, ventilation, healthy pulmonary endothelium and the microvascular structure support thrombopoiesis. We also show a critical role for the actin regulator Tropomyosin 4 in the final steps of platelet formation in lung vasculature. This work reveals the mechanisms of thrombopoiesis in lung vasculature and informs approaches to large-scale generation of platelets.

Loss of zinc transporters ZIP1 and ZIP3 augments platelet reactivity in response to thrombin and accelerates thrombus formation in vivo

Zinc (Zn2+) is considered as important mediator of immune cell function, thrombosis and haemostasis. However, our understanding of the transport mechanisms that regulate Zn2+ homeostasis in platelets is limited. Zn2+ transporters, ZIPs and ZnTs, are widely expressed in eukaryotic cells. Using mice globally lacking ZIP1 and ZIP3 (ZIP1/3 DKO), our aim was to explore the potential role of these Zn2+ transporters in maintaining platelet Zn2+ homeostasis and in the regulation of platelet function. While ICP-MS measurements indicated unaltered overall Zn2+ concentrations in platelets of ZIP1/3 DKO mice, we observed a significantly increased content of FluoZin3-stainable free Zn2+, which, however, appears to be released less efficiently upon thrombin-stimulated platelet activation. On the functional level, ZIP1/3 DKO platelets exhibited a hyperactive response towards threshold concentrations of G protein-coupled receptor (GPCR) agonists, while immunoreceptor tyrosine-based activation motif (ITAM)-coupled receptor agonist signalling was unaffected. This resulted in enhanced platelet aggregation towards thrombin, bigger thrombus volume under flow ex vivo and faster in vivo thrombus formation in ZIP1/3 DKO mice. Molecularly, augmented GPCR responses were accompanied by enhanced Ca2+ and PKC, CamKII and ERK1/2 signalling. The current study thereby identifies ZIP1 and ZIP3 as important regulators for the maintenance of platelet Zn2+ homeostasis and function.

RhoA/Cdc42 signaling drives cytoplasmic maturation but not endomitosis in megakaryocytes

Megakaryocytes (MKs), the precursors of blood platelets, are large, polyploid cells residing mainly in the bone marrow. We have previously shown that balanced signaling of the Rho GTPases RhoA and Cdc42 is critical for correct MK localization at bone marrow sinusoids in vivo. Using conditional RhoA/Cdc42 double-knockout (DKO) mice, we reveal here that RhoA/Cdc42 signaling is dispensable for the process of polyploidization in MKs but essential for cytoplasmic MK maturation. Proplatelet formation is virtually abrogated in the absence of RhoA/Cdc42 and leads to severe macrothrombocytopenia in DKO animals. The MK maturation defect is associated with downregulation of myosin light chain 2 (MLC2) and β1-tubulin, as well as an upregulation of LIM kinase 1 and cofilin-1 at both the mRNA and protein level and can be linked to impaired MKL1/SRF signaling. Our findings demonstrate that MK endomitosis and cytoplasmic maturation are separately regulated processes, and the latter is critically controlled by RhoA/Cdc42.

[Control of the legal practice of euthanasia in Belgium]

The Belgian law legalizing euthanasia under strict conditions came into effect September 22, 2002. Any physician performing euthanasia has to complete a registration document and to send it within four days to a federal commission whose mission is to verify that the legal conditions were fulfilled. From September 22, 2002 to December 31, 2013, 8.767 documents have been registered and analyzed by this commission. They are described in six reports referred to Parliament. The present paper analyzes the work of this commission and answers the criticisms concerning its quality and its efficiency. The allegations that clandestine euthanasia's escaping any control are performed are also discussed. In conclusion, it appears that the legal obligations concerning the practice of euthanasia in Belgium are fully effective.

[Management of requests for euthanasia. Discussion of cases]

Since September 2002, more than 2.000 legal euthanasia's were performed in Belgium. The present paper reviews the necessary steps to be followed by the physician for a correct achievement of the process initiated by the patient's demand to die. Interpretation of the legal conditions to be respected by the physician is discussed from reports of ten cases of requests for euthanasia.

[Depenalized practice of euthanasia in Belgium: evolution from 2002 to 2005 and interpretation of the differences between the north and the south of the country]

The euthanasia's performed, in accordance with the law of may 28, 2002, between September 22, 2002 and December 31, 2003 and between January 1, 2004 and December 31, 2005 are respectively analyzed in two successive reports of the federal commission for control and evaluation of euthanasia, based on the registration documents referred by the physicians to this commission. The present paper compares the data of those two reports and analyses the evolution of the application of the law. Apart from the number of euthanasia's per year, much greater in 2004-2005, the statistical data are very similar. The important difference in the number of registration documents written in French and in Dutch, already noted in the first report, is confirmed in 2004-2005. An interpretation is proposed.

[Two years of legal practice of euthanasia in Belgium: comparison with the Netherlands. First evaluation in a palliative care unit]

The Belgian law relative to euthanasia prescribes that a physician performing an euthanasia has to complete a registration document and to send it within 4 days to the federal commission for control and evaluation of euthanasia. The 259 first documents are described in the report of the commission referred to Parliament on September 17, 2004. The present paper analyses this report and compares its most important data with those published in the Netherlands: apart from the total number of euthanasia's, much smaller in Belgium, and apart from aspects which are specifically related to the Belgian law, the statistical data are very similar in both countries. The difference in the number of registration documents written in French and in Flemish is analyzed and discussed. A first evaluation of the application of the law in a supportive and palliative care unit is reported.

[Depenalized practice of euthanasia in Belgium]

The first report of the federal commission of control and evaluation of euthanasia, transmitted to Parliament on September 17, 2004, gives interesting data concerning the practice of euthanasia in Belgium under the conditions specified by the law of May 28, 2002. The present paper analyses and comments upon this report.

Slip prevention: validation of duplicates reproducing industrial floor surface state microgeometry

The present study falls within the scope of work on the prevention of slips occurring on industrial workplace floor surfaces. Floor microgeometry is a determining factor in anti-slip flooring. Industrial environment-based quantification of floor microgeometrical properties is more restricting than laboratory quantification. The aim of the present study was to develop a duplication technique allowing reproduction of in situ floor microgeometry so as to be able to quantify this microgeometry in the laboratory. Duplicates were produced from a sample of five industrial floors. Surface microgeometry was characterized for both industrial floors and associated duplicates in order to study their microgeometrical changes following the duplicating operation. The purpose of this process was to reach a conclusion on the "reliability" of the duplication technique, on which the use of such duplicates depends. Parameters established from digitalized surfaces reveal differences of less than 5% between duplicates and original floor and this enables us to conclude that these duplicates offer a high degree of reliability with respect to results dispersion.

[Terminal medical interventions: psychosocial, medical, ethical and legal aspects]

We give an overview of the available medical solutions to help a patient with refractory symptoms at the end of his life. Patient "competence" must first be evaluated and, even if their diagnosis is difficult, organic mental disorders and depression must be diagnosed and adequately treated to allow a real, personal and honest dialog. Administration of high doses of morphine is frequently used at the end of life not only to fully relieve pain but also to accelerate death, even if this is not clearly stated. This technique is not devoid of hypocrisy and high doses of morphine can have quite unpleasant side effects. Treatment withdrawal or withholding is generally not sufficient to allow a correct end of life. The arrest of ventilation, dialysis, artificial nutrition and even more hydration must often be coupled with techniques inducing unconsciousness, which makes imprecise the limits between such a "passive" ending of life and "active" euthanasia. The technique of terminal sedation, frequently based on the use of midazolam, has been more recently introduced in some palliative care units. Such a "controlled sedation" is supposed to allow a "natural" death by inducing a profound sleep. In opposition with active euthanasia, which allows a quiet and rapid death at a moment chosen by the patient himself, this technique of "sedation" has an undetermined duration, has legal implications which could be viewed as quite similar as the ones of euthanasia, and, moreover, this prolonged agony can be extremely stressful and distressing for the family. Medical-assisted suicide is allowed in The Netherlands under the same conditions as euthanasia. Death is generally obtained after a few hours but the technique is not always successful and the process of death can sometimes be prolonged and uncomfortable. This technique can nevertheless be preferred by some physicians and patients. As compared to active euthanasia, the proportion of medically-assisted suicides (1/6) is low in The Netherlands. Euthanasia is the only technique able to induce a peaceful and rapid death. The proportion of various techniques to actively induce death is probably quite similar in our country than in The Netherlands but, most of the time, these interventions occur at the very end of life when the patient is no longer able to participate in the decision process and thus occur without his explicit request. We think that, as for all medical decisions, the use of one or the other of these various techniques should be selected after a quiet and free discussion between the patient and his physician, preferably in advance and not in a situation of emergency and panic.

Electrophysiologic effects of intravenous xamoterol in patients with sinus node dysfunction

The electrophysiologic effects of xamoterol were studied in ten patients with electrophysiologic evidence of sinus node dysfunction. A significant shortening of mean sinus cycle length, maximal corrected sinus-node recovery time, and the mean of the three longest corrected sinus-node recovery times was observed after intravenous administration of 0.1 mg/kg of xamoterol. The atrioventricular (AV) conduction time and the effective and functional refractory periods of the AV node were shortened as the effective refractory period of the atrium. These effects suggest that xamoterol could be tried safely for the treatment of patients with moderate symptoms due to sinus-node disease.

Relationships between catastrophic cognitions and body sensations in anxiety disordered, mixed diagnosis, and normal subjects

Clark's (Behaviour Research and Therapy, 24, 461-470, 1986) cognitive model proposes that panic attacks result from the catastrophic misinterpretation of certain body sensations. The present study examined correlations between feared body sensations and catastrophic cognitions. It was hypothesized that regardless of diagnostic status meaningful correlations between sensations and cognitions would be obtained. Three groups--anxiety disordered patients (n = 33), nonanxiety disordered patients (n = 57), and normals (n = 60)--completed the Agoraphobic Cognitions Questionnaire and the Body Sensations Questionnaire. Results generally supported the hypothesis and the cognitive model of panic and anxiety. Limitations of the correlational methodology are discussed, and treatment implications are noted.

Anterior mitral valve aneurysm perforation secondary to aortic valve endocarditis detected by Doppler colour flow mapping

We report a case of mitral valve aneurysm formation and perforation, secondary to Streptococcus sanguis endocarditis of the aortic valve. Aneurysm formation was documented by cross-sectional echocardiography and its perforation was established by Doppler colour flow mapping, and subsequently confirmed at surgery.

Diastolic function and modifications of left ventricular architecture in ultraendurance athletes

Although diastolic function is altered in left ventricular hypertrophy due to aortic stenosis or systemic hypertension, it has been shown to be normal in athletes. To analyze the reason for this discrepancy, we have studied left ventricular masses and volumes and diastolic flow velocities in 13 ultraendurance athletes and in 8 sedentary subjects as a control group by M-mode (TM), two-dimensional (2D) and Doppler echocardiography. Significant differences in the measurements of mass and volume have been found depending upon the method used. Considering that two-dimensional echocardiography is more appropriate for estimations of LV mass and LV volume, especially when the shape of the left ventricle is modified, overestimation of LV mass and underestimation of LV volume in ultraendurance athletes by TM could be explained by an elongation of LV cavity in athletes. Doppler velocimetry showed similar results in athletes and control subjects. We suggest that those LV configurational changes partly explain the preservation of diastolic function in athletes by restoring in diastole the energy stored in systole.

Noninvasive imaging of left coronary arteriovenous fistula

We investigated a patient with coronary arteriovenous fistula (CAVF) by two-dimensional echocardiography (2-DE), cardiac Doppler, cardiac catheterization and nuclear magnetic resonance (NMR). These investigations clearly showed the abnormal vascular structures. NMR is another valuable noninvasive and safe method of confirming the presence of a CAVF.

A study of the correlation between Doppler and cross-sectional echocardiography in the determination of the mitral valve area

Fifty-five consecutive adult patients with mitral stenosis (MS) were investigated by Doppler echocardiography, to assess the severity of MS. The measurement of mitral valve area (MVA) by cross-sectional echocardiography (CSE) was considered as the reference method, because catheterization data are often inadequate when combined lesions are present. Doppler MVA was calculated from apical mitral flow using the pressure half-time method. Adequate Doppler recordings (52 on 55) were easier to obtain than adequate CSE images[47]. The correlation between both methods was excellent (r = 0.90, SEE: 0.42 cm2) despite systematic underestimation of MVA by Doppler versus CSE. From our data, the following regression equation could be drawn, providing MVA from Doppler measurements: MVA = 250 (pressure half-time)-1 +0.15, where the area is in cm2 and half-time in ms. Both severe and mild MS were identified by Doppler with enough accuracy for clinical use. Reproducibility, inter and intraobserver variability were better for Doppler than for CSE. We conclude that Doppler seems particularly suitable for noninvasive quantification of MS and for patient follow-up.

[Lipomatous hypertrophy of the interauricular septum. Morphological and electrocardiographical aspects]

The authors report a case of lipomatous hypertrophy of the interatrial septum diagnosed by echocardiography and confirmed by computerised tomography. The electrocardiogram showed an intra-atrial conduction defect considered to be virtually pathognomonic of this condition. The differential diagnosis and clinical implications of this abnormality, which is usually a fortuitous finding, are discussed in the light of recent publications. A precise diagnosis avoids confusion with other pathologies necessitating specific treatment such as intra-atrial thrombi and tumours.

Placebo-controlled study of lisinopril in congestive heart failure: a multicentre study

A double-blind randomised, parallel, placebo-controlled study was performed in patients with congestive heart failure, at 13 centres in 10 countries, to assess the efficacy and safety of lisinopril, a new angiotensin-converting enzyme inhibitor. After a 2-week run-in period, 130 patients receiving digoxin and/or diuretics were randomised to 12 weeks of treatment with lisinopril 5 mg daily (87 patients) or with placebo (43 patients), with an option to increase lisinopril dosage to 10 or 20 mg. Patients treated with lisinopril improved significantly more than placebo-treated patients (p less than 0.05) for all clinical parameters except oedema and paroxysmal nocturnal dyspnoea. Left ventricular ejection fraction rose by 8% in lisinopril patients compared to 2% in the placebo group, while the cardiothoracic ratio and echocardiographic end systolic diameter fell in the lisinopril group (p less than 0.01) but not in the placebo group. Exercise duration was greater in the lisinopril group at all timepoints, and the increase in exercise duration at 12 weeks was greater by more than 2 min in the lisinopril group as compared to the placebo group (p less than 0.01). Changes in clinical and noninvasive parameters such as the New York Heart Association status, were well correlated with changes in exercise duration. Four patients in the lisinopril group and three in the placebo group died in this study, and there were 31 adverse clinical experiences in the 87 lisinopril-treated patients compared to 13 in the 43 placebo-treated patients. We conclude that lisinopril in doses of 2.5-20 mg/day is well tolerated and effective in patients with heart failure who are receiving digitalis and diuretics.

Variations of normal sinus node function in relation to age: role of autonomic influence

An electrophysiological study of sinus node function, including measurements of resting heart rate, maximal corrected sinus node recovery time and sinoatrial conduction time, was performed in 30 patients, 12-79 years of age, without any clinical, electrocardiographic or electrophysiological evidence of sinus node disease. To analyse autonomic influences, variables were measured before and after sympathetic and parasympathetic blockade. No significant correlations were observed between age and electrophysiological measurements of sinus node function at the control study or after sympathetic blockade. In contrast, the electrophysiological parameters of intrinsic sinus node activity were correlated with age and showed a progressive lengthening of mean sinus cycle length, of maximal corrected sinus node recovery time and of sinoatrial conduction time. In addition, measurements after vagolysis suggest a progressive decrease of parasympathetic activity with increasing age. These data also indicate that the respective role of the two components of the autonomic nervous system vary with increasing age: parasympathetic activity predominates in younger subjects; sympathetic and parasympathetic tones are equilibrated in older subjects. The normal sinus node function represents an equilibrated system: in parallel with ageing of the intrinsic properties of the sinus node, parasympathetic activity decreases so that basal properties remain stable throughout life.

Pulsed Doppler regurgitant flow patterns of normal valves

Although Doppler echocardiography allows recording of regurgitant turbulent flow patterns in normal persons, sparse information is available concerning the incidence, characteristics and mechanism of these flow patterns. Therefore, pulsed Doppler echocardiograms were recorded in 25 normal persons to detect regurgitation. A regurgitant turbulent flow pattern was recorded at the pulmonic valve in 23 subjects (92%), covered up to 81% of the diastole and could never be recorded in early diastole. An early to midsystolic regurgitant flow pattern was recorded at the mitral valve in 10 subjects (40%) and covered up to 60% of systole. A similar regurgitant flow was recorded at the tricuspid valve in 11 subjects (44%) and was holosystolic in 1 subject. An early diastolic regurgitant flow with low maximal velocities and rapid decrease in velocities was recorded at the aortic valve in 8 subjects (33%) and covered up to 26% of the diastole. In no person could those flows be recorded farther than 1 cm proximal to the valve closure. Whatever the still-debated mechanisms of those regurgitant flow patterns in normal subjects, one should be aware of their existence and characteristics when assessing valvular function by Doppler.

Reproducibility of electrophysiologic parameters of extrinsic sinus node function in patients with and without sick sinus syndrome

In a group of 50 patients we investigated the daily reproducibility of the resting heart rate (RHR), the maximal corrected sinus node recovery time (CSNRTM), the pacing rate at which the CSNRTM occurred (OP), and the sinoatrial conduction time (SACT) during basal state. The study population was divided into two groups according to the presence or absence (as evidenced during the initial electrophysiologic study) of sinus node disease: group I included 35 patients with normal sinus node function, and group II included 15 patients with sick sinus syndrome. The electrophysiologic study was repeated approximately at the same hour and under similar conditions after an interval of at least two days (mean: 3.2 days for group I and 4.7 days for group II). The results showed good reproducibility with the exception of RHR in group I which slightly but significantly decreased in the second electrophysiologic study. The daily variations of the sinus node parameters appeared to be of similar levels in the two groups except for the CSNRTM; this parameter showed wide variations in single values in both groups, more marked in group II than in group I. Furthermore, if the CSNRTM and/or SACT were normal, it was likely that they would remain normal whatever the electrophysiologic status of the patient. Inversely, the change of status from abnormal to normal CSNRTM or SACT was not uncommon in patients with electrophysiologic signs of sinus node disease.

Pretreatment of rats with anticollagen IgG renders them resistant to active type II collagen arthritis

Intravenous administration of 24 mg of affinity-purified rat anticollagen IgG induced a polyarthritis in recipient rats within 48 hr. This polyarthritis was transient and hind paw diameters returned to normal values within 12 days. IgG and C3 could be detected on the articular cartilage by immunofluorescence up to 16 days after antibody administration. Administration of 24 mg of rat anticollagen IgG to these antibody-treated rats did not induce a second phase of polyarthritis. In addition, recovered rats that had been pretreated with antibody were resistant to arthritis when Type II collagen was administered intradermally. In these rats, serum anticollagen IgG levels were significantly lower than in control rats which were not treated with antibody. Pretreatment of rats with anticollagen IgG did not have an effect on the severity or the incidence of adjuvant-induced arthritis. In addition, pretreatment of rats with anticollagen IgG did not have an effect on the development of a humoral response to ovalbumin.

Sensitivity and specificity of pulsed Doppler echocardiography in detection of aortic and mitral regurgitation

In order to assess the value of pulsed Doppler echocardiography in detection of valvular regurgitation, 63 patients were evaluated for aortic and/or mitral regurgitation using pulsed Doppler echocardiography and selective cineangiography. The Doppler study was considered as positive when a turbulent flow was detected below the aortic valve for aortic insufficiency and behind the mitral valve for mitral insufficiency on a graphic display (time interval histogram) when technically adequate and/or on an audiosignal. These results were compared with standard angiographic evaluation of the regurgitation: pulsed Doppler echocardiography had 94% sensitivity and the specificity rate was very high (87.5%) even for mild regurgitation. Thus, Doppler technique is highly specific and sensitive in detection of aortic and mitral regurgitation when both audiosignal and time-interval histogram are simultaneously performed.

Right atrial thrombus leading to pulmonary embolism

Cross sectional and M mode echocardiography detected a large right atrial mass in a 70 year old man five days after admission. Three weeks later he developed acute respiratory failure due to a pulmonary embolism. Necropsy showed that the atrial mass was a thrombus. Thus echocardiography should be performed in patients with pulmonary emboli to examine the right cardiac cavities. The need for emergency surgery could then be assessed.

Hemodynamic effects of dobutamine in patients below and over 65 years, with left heart failure secondary to an acute myocardial infarction

The cardiac response to sympathomimetic agents has been reported to be reduced in the elderly. We studied the hemodynamic effects of dobutamine in two groups of patients with acute myocardial infarction (AMI) and left heart failure: group A included 10 patients aged 65 years or less and group B 10 others older than 65. After a 1-hour infusion the increase in cardiac index was highly significant in both groups (27%, p less than 0.001 and 25%, p less than 0.001), and the decrease in pulmonary wedge pressure was greater in group A (42%, p less than 0.001 and 17%, p less than 0.02). The increase in double product was similar in both groups (14%, p less than 0.001 and 18%, p less than 0.005); nevertheless the 4 patients developing angina pectoris during dobutamine infusion were over 65 years. We conclude that dobutamine remains effective in the elderly with AMI and left heart failure but is less well tolerated.

Hemodynamic effects of concurrent administration of metoprolol and tocainide in acute myocardial infarction

We evaluated the hemodynamic effects of combined administration of metoprolol and tocainide in nine patients with uncomplicated acute myocardial infarction. After 24 h of treatment with oral metoprolol (50 mg q.8 h), intravenous tocainide was given (750 mg over 15 min), followed by oral administration of both drugs (50 mg metoprolol q.8 h; 800 mg tocainide, then 400 mg q.8 h). Hemodynamic variables were measured before and after 25 h of oral metoprolol treatment, immediately after intravenous tocainide (at 15 and 30 min), and then during continued oral treatment with both drugs (at 2 h 15 min and 25 h 45 min). Following injection of tocainide, cardiac index changed significantly (2.7-2.3 L/min . m2; p less than 0.01), but the increases in pulmonary wedge pressure (9-13 mm Hg) and total systemic resistance (15.9-18.1 IU) were not significant. During the continued oral treatment with both metoprolol and tocainide no significant hemodynamic interaction was observed. We conclude that the injection of tocainide can slightly and transiently depress left ventricular function in patients treated with metoprolol.