Silent cerebral embolism in patients with rheumatic mitral valve disease

Electroencephalograms were recorded in 71 stroke-free patients suffering from mitral valve disease, complicated by atrial fibrillation in 33. The incidence of EEG abnormalities was not related either to the presence or absence of atrial fibrillation or to the type of valve lesion present, and did not differ significantly from the incidence observed in the general population. The findings suggest that occurrence of symptomatically silent emboli is not a feature of rheumatic mitral valve disease.     

Programmed atrial and ventricular stimulation in patients with mitral valve prolapse--a personal experience]

Electrophysiological tests were performed in 60 patients aged between 18 and 63 years (mean age 38 years), and divided into two groups: with mitral valve leaves prolapse syndrome, and without this abnormality, in whom no other heart disease was diagnosed. Refraction of the right atrium, atrio-ventricular node, and right ventricle was evaluated together with cardiac response to different types of electrostimulation. A supraventricular dysrhythmia (most frequently atrial fibrillation) has been produced in 17 patients (42.5%) with mitral valve leaves prolapse syndrome whereas in the control group the same was produced in 2 patients (10%). Programmed stimulation of the ventricles did not produce ventricular tachycardia in none patient of both groups. Multiple ventricular beats have been produced in 3 patients with mitral valve prolapse syndrome and pairs of ventricular beats in other 3 patients of this group. Results suggest that "arrhythmogenic tendency", especially supraventricular dysrhythmia is more frequent in patients with mitral valve prolapse syndrome than in the general population.     

Molecular weight of detergent-solubilized prostaglandin-F2 alpha receptor from bovine corpora lutea

A prostaglandin F2 alpha receptor localized in plasma membranes of bovine corpus luteum cells was solubilized by treatment with Triton X-100. Sepharose chromatographies of ([3H]prostaglandin F2 alpha)-receptor complex gave a Stokes' radius of 630 nm. In the absence of detergent, aggregated forms of the receptor appeared. Sedimentation experiments of solubilized receptor in sucrose/H2O and sucrose/2H2O density gradients gave the following values: sedimentation coefficient (S20, w) 4.6 S; partial specific volume (VB) 0.78 cm3/g and frictional ratio (f/fo) 1.6. Based on the sedimentation coefficient and the Stokes' radius and assuming that the receptor is a non-glycosylated protein the molar mass of the receptor-(Triton X-100) complex was 144000 g/mol. The VB value indicated that ca. 26% of the weight represented bound detergent and that the molecular weight of the prostaglandin F2 alpha receptor is approximately 107000.     

Quantitative analysis of mitral valve morphology in atrial functional mitral regurgitation using real-time 3-dimensional echocardiography atrial functional mitral regurgitation

Background

Atrial fibrillation (AF) can result in atrial functional mitral regurgitation (MR), but the mechanism remains controversial. Few data about the relationship between the 3-dimensional morphology of the MV and the degree of MR in AF exist.

Methods

Real-time 3-dimensional transesophageal echocardiography (3D-TEE) of the MV was acquired in 168 patients with AF (57.7% persistent AF), including 25 (14.9%) patients with moderate to severe MR (the MR+ group) and 25 patients without AF as controls. The 3-dimensional geometry of the MV apparatus was acquired using dedicated quantification software.

Results

Compared with the group of patients with no or mild MR (the MR- group) and the controls, the MR+ group had a larger left atrium (LA), a more dilated mitral annulus (MA), a reduced annular height to commissural width ratio (AHCWR), indicating flattening of the annular saddle shape, and greater leaflet surfaces and tethering. MR severity was correlated with the MA area (r²?=?0.43, P?<?0.01) and the annulus circumference (r²?=?0.38, P?<?0.01). A logistic regression analysis indicated that the MA area (OR: 1.02, 95% CI: 1.01–1.03, P?<?0.01), AHCWR (OR: 0.24, 95% CI: 0.14–0.35, P?=?0.04) and MV tenting volume (OR: 3.24, 95% CI: 1.16–9.08, P?=?0.03) were independent predictors of MR severity in AF patients.

Conclusions

The mechanisms of “atrial functional MR” are complex and include dilation of the MA, flattening of the annular saddle shape and greater leaflet tethering.

     

Arrhythmia in patients with mitral valve prolapse]

An incidence of cardiac arrhythmias was evaluated in 119 patients with mitral valve prolapse. The disease was made basing on the results of clinical symptoms, echo-, angio- and phonocardiography. Electrocardiograms were recorded from the standard 12 lead and Holter technique for 24 hours in each patient to assess present arrhythmias. It was found that the most frequent cardiac arrhythmias accompanying mitral valve prolapse are ventricular extrasystolic contractions of Lown's class 1a and 1b. Only examination of strictly selected groups of patients (age groups with or without co-existing mitral valve insufficiency for adequate period of time) will facilitate precise evaluation of an incidence of different cardiac arrhythmias accompanying the underlying disease.     

Fatigue exhaustion of the mitral valve tissue

Biomechanics and Modeling in Mechanobiology - Sudden failure and rupture of the tissue is a rare but serious short-term complication after the mitral valve surgical repair. Excessive cyclic loading...     

Subcellular distribution of alpha 1-adrenergic receptors in rat liver

The distribution of alpha 1-adrenergic receptors in rat liver subcellular fractions was studied using the alpha 1-adrenergic receptor ligand [3H]prazosin. The highest number of [3H]prazosin binding sites was found in a plasma membrane fraction followed by 2 Golgi and a residual microsomal fraction, the numbers of binding sites were 1145, 845, 629 and 223 fmol/mg protein, respectively. When the binding in these fractions was compared with the activity of plasma membrane 'marker' enzymes in the same fractions a relative enrichment of [3H]prazosin binding sites was found in the residual microsomes and one of the Golgi fractions. Photoaffinity labelling with 125I-arylazidoprazosin in combination with SDS-polyacrylamide gel electrophoresis revealed the specific binding to 40 and 23 kDa entities in a Golgi fraction, while in plasma membranes the binders had an apparent molecular mass of 36 and 23 kDa. When [3H]prazosin was injected in vivo into rat portal blood followed by subcellular fractionation of liver, a pattern of an initial rapid decline and thereafter a slow decline of radioactivity was noted in all fractions. Additionally, in the two Golgi fractions a transient accumulation of radioactivity occurred between 5 and 10 min after the injection. The ED50 values for displacement of [3H]prazosin with adrenaline was lowest in the plasma membrane fraction, followed by the residual microsomes and Golgi fractions, the values were 10(-6), 10(-5) and 10(-4) mol/l, respectively. On the basis of lack of correlation between distribution of alpha 1-adrenergic antagonist binding and adenylate cyclase activity, differences in the molecular mass of alpha 1-adrenergic antagonist binders, differences in the kinetics of in vivo binding and accumulation of [3H]prazosin and also differences in agonist affinity between plasma membrane and Golgi fractions, it is concluded that alpha 1-adrenergic receptors are localized to low-density intracellular membranes involved in receptor biosynthesis and endocytosis.     

Comparative analysis of oncofetal fibronectin and tenascin-C expression in right atrial auricular and left ventricular human cardiac tissue from patients with coronary artery disease and aortic valve stenosis

Aortic valve stenosis (AVS) and coronary artery disease (CAD) are accompanied by changes in the cardiac extra cellular matrix (cECM) including the re-expression of oncofetal fibronectin (Fn) and tenascin-C (Tn-C) variants. Human antibodies against these variants are usable for targeted therapy. Aim of the study was the comparative analysis of cECM remodelling in tissue samples from right atrial auricle (RAA) and left ventricular septum (LVS). RAA and LVS specimens from 30 patients (17?×?AVS; 13?×?AVS+CAD) were analysed with respect to histological changes and ECM remodelling using PCR based ECM gene expression profiling. Re-expression of ED-A(+) Fn and A1(+) Tn-C was investigated on the mRNA and on the protein level. For immunofluorescence, human recombinant small immunoprotein (SIP) format antibodies were used. There was a positive correlation of the grade of histological changes in RAA and corresponding LVS samples (r?=?0.695). ECM gene expression levels were higher in LVS compared to RAA. For 24 genes, a corresponding relevant (>2.5-fold) up- or down-regulation in RAA and LVS occurred. Using SIP antibodies, a positive correlation of protein deposition levels in RAA and corresponding LVS (r?=?0.818) could be shown for ED-A(+) Fn. Cardiac tissue remodelling is likely a process involving the entire heart reflected by intra-individually comparable histology and cECM changes in RAA and LVS samples. ED-A(+) Fn might be an excellent target for an antibody-mediated delivery of diagnostic or therapeutic agents. The RAA is a valuable and representative tool to evaluate cardiac remodelling and to plan individualized therapy.     

Coexistence of von Willebrand's disease with mitral valve prolapse]

The authors present the case of mitral valve prolapse. In a young woman with three-year history of systematically treated epilepsia mitral valve prolapse with a spurious string within left ventricle has been diagnosed echocardiographically in coincidence with the symptoms of haemorrhagic diathesis of von Willebrand type in form of haemoptysis and or/massive haemorrhages in mouth occasionally being preceded by heart rhythm disturbances. No local changes have been observed in otorhinolaryngologic examination, bronchoscopy and gastroscopy. Possible mutual dependence of 3 above stated abnormalities is being discussed. It is not excluded, that mitral prolapse may constitute the primary entity and epilepsia is of secondary character as a result of cerebral ischaemic incidents or of cerebral embolism. It is also a matter of discussion to what extent abrupt haemodynamic disturbances connected with critical fall of systemic blood pressure due to mitral prolapse may influence the haemorrhagic episodes.     

Subcellular distribution of alpha 2-adrenergic receptors, pertussis-toxin substrate and adenylate cyclase in human platelets.

The subcellular distribution of the alpha 2-adrenergic receptor, pertussis-toxin substrates (Gi, the inhibitory G-protein) and adenylate cyclase was determined in human platelets. The alpha 2-adrenergic receptor and pertussis-toxin substrate activity codistribute with surface membranes identified by a novel fluorescent-lectin method. The platelet granule fractions did not contain detectable Gi. Only 2-4% of the total pertussis-toxin substrate activity appears in soluble fractions, and this amount was not increased upon addition of purified beta gamma units or after pretreatment of platelets with adrenaline. There is no evidence for compartmentation of the alpha 2-adrenergic receptor or Gi to account for the low-affinity component of agonist binding to the alpha 2-adrenergic receptor in human platelet membranes. Translocation of Gi from plasma membrane to platelet cytosol or granules does not appear to play any significant role in the mechanism of alpha 2-receptor-mediated platelet activation.     

Increased prevalence of mitral valve prolapse in patients with migraine.

Patients with classic migraine (69 women and 31 men) selected randomly from a practice list of over 1000 were matched for age, sex and neighbourhood with 100 people who did not have headache problems, and both groups underwent M-mode and two-dimensional echocardiography and clinical examination by cardiologists blinded to the subjects'' clinical status. The mean ages were 34.9 +/- 11.3 years for the migraine group and 33.1 +/- 9.9 years for the control group. Definite and possible mitral valve prolapse (MVP), diagnosed according to predefined echocardiographic criteria, were found about twice as often in the migraine group as in the control group (in 15 v. 7 and 16 v. 8 patients respectively); the echocardiograms were definitely normal in 69 migraine patients and 85 controls (chi 2 = 8.39, p less than 0.025). Altogether 25% of the migraine group and 11% of the control group had evidence of MVP from a combination of the echocardiographic and auscultatory findings (chi 2 = 5.72, p less than 0.025). The odds ratio was 2.7, with 95% confidence limits of 1.17 and 6.29. The association between migraine and MVP has implications for the understanding of platelet abnormalities and episodes of cerebral ischemia occurring in both these conditions.