The paper presents new original data on the Devonian felsic volcanism of the NW Rudny Altai (Russia) in the west of Central Asian Orogenic Belt (CAOB) – the front part of the Altai convergent margin ...of the Siberian continent. Two geochemical types of subvolcanic rhyolites were emplaced synchronously with the bimodal rhyolite-basalt association, which began to form in the end-Emsian, and clearly manifested on the border of the Givetian and the Frasnian. The rhyolites yield zircon U-Pb ages of ca. 390 Ma (R1-type) and 380 Ma (R2- and R3-types), reflecting two peaks of the volcanic activity. Most of these rocks have extreme petrochemical characteristics of high SiO2 contents and have contrast Na/K ratios. Their compositions are transition between calc-alkaline and tholeiite series: (La/Yb)n ~ 2–7, Zr/Y ~ 4 (Zr < 350 ppm) and La/Sm ~ 0.55–1. Rhyolites bear the distinctive geochemical signature of A-type felsic magma, such as enrichments in Zr, Nb, Y and Ce (>350 ppm), Zr (>250 ppm), and high Ga/Al (>2.6) values. The island-arc-like R1-rhyolite formed immediately after the beginning of rifting due to widespread crustal melting under reduced conditions. The generation of rift-like R2- and R3-rhyolites took place under non-equilibrium conditions, synchronously with the rise in the upper crust of Givetian-Frasnian basic magmas, as a result of the active lithospheric extension and high thermal input from the underlying hot mantle. We propose an extension regime in the transition area between the island-arc and back-arc basin for the origin of rhyolites. The study of the Devonian volcanism of the Rudny Altai gives important information about the processes that occurred at the initial stage of the formation of the Altai convergent margin.
In the front of the Altai convergent margin (NW Rudny Altai) of the Siberian continent two different geochemical types of subvolcanic rhyolites were emplaced consistently between ~390 and 380 Ma. Progressive rifting is assumed, as indicated by consistent generation, first island-arc-like rhyolites (R1), and then rift-like rhyolites (R2 and R3). The arc-like R1-rhyolite formed immediately after the beginning of rifting due to widespread crustal melting under reduced conditions. The R2- and R3-rhyolite was generated under non-equilibrium conditions, synchronously with the rise of basalts in the upper crust, as a reflection of the prolonged lithospheric extension and high thermal input from underlying hot mantle. Display omitted
•Early Devonian tectono-thermal evolution in the Central Asian Orogenic Belt•The rift-related bimodal-type rhyolites volcanism in a rear-arc/back-arc basin setting•Two different geochemical types of rhyolites were emplaced between ~390 and 380 Ma.
Aortic intramural hematoma (IMH) is a clinical condition that has still not been completely defined. We conducted a meta-analysis of reported cases and analyzed the demographic profiles, imaging ...modalities, pathologic sites, and treatment strategies in relation to outcome in 143 patients with IMH. We performed an English language search of Medline for manuscripts with the keywords “aortic diseases,” “aorta AND hematoma,” and “intramural hematoma.” Data from 143 reported cases were extracted. IMH of the aorta has a reported incidence of 5% to 20% among patients with acute aortic syndromes and a mortality rate of 21%. Most patients were men (61%) and median age was 68 years (range 15 to 88). Hypertension was a predisposing factor in 53% of the patients. Most patients had chest and/or back pain (80%). Transesophageal echocardiography, computer tomographic scan, or magnetic resonance imaging may be effectively used to diagnose this condition. There is no difference in the overall mortality rates in Stanford type A versus type B patients. Patients with Stanford type A IMH who underwent surgery, compared with those who underwent medical management, had a significantly better prognosis (14% vs 36% mortality, respectively, p <0.02). Patients in Stanford group A who received medical treatment had a higher mortality rate than those in group B who received medical treatment (36% vs 14% mortality respectively, p <0.02). In type B patients, medical and surgical outcomes were similar.
Ninety-one patients with dilated cardiomyopathy were studied by two-dimensional, pulsed, and color Doppler echocardiography (1) to detect and quantify mitral regurgitation (MR), (2) to record apical ...flow velocities in systole and diastole, and (3) to detect the presence of left ventricular thrombi. MR was detected in 57% of the patients and thrombi were present in 40%, but the occurrence of both MR and thrombus was rare (8%). Apical flow velocity was significantly higher throughout the cardiac cycle in the group with MR (diastole 15 +/- 7 vs 9 +/- 7 cm/sec; systole 29 +/- 12 vs 16 +/- 13 cm/sec; p less than 0.001 for both), accounting for the rarity of thrombi in this group. Follow-up data on 89% of the patients showed markedly decreased survival in the group with MR (22% vs 60% at 32 +/- 6 months, p less than 0.005), and this was evident even in patients with mild MR. Thus although MR is a noninvasively obtainable marker of a large subgroup of patients with dilated cardiomyopathy "protected" from left ventricular thrombus formation, it is a sensitive marker of decreased survival.
Acquired immunodeficiency syndrome is a serious problem worldwide. Recent advances in the knowledge about human immunodeficiency virus (HIV) replication and the treatment of HIV infection have ...improved survival in HIV patients. Because of the longer survival in HIV patients, the more manifestations of late-stage HIV infection will be seen, including HIV-related cardiac diseases. The common cardiac manifestations in patients with the acquired immunodeficiency virus are pericardial effusion, myocarditis, dilated cardiomyopathy, endocarditis, pulmonary hypertension, malignant neoplasms, and drug-related cardiotoxicity. This review focuses on these cardiac manifestations in patients with the acquired immunodeficiency syndrome.Arch Intern Med. 2000;160:602-608-->
: Accumulation of δ‐aminolevulinic acid (ALA), as it occurs in acute intermittent porphyria (AIP), is the origin of an endogenous source of reactive oxygen species (ROS), which can exert oxidative ...damage to cell structures. In the present work we examined the ability of different antioxidants to revert ALA‐promoted damage, by incubating mouse astrocytes with 1.0 mm ALA for different times (1–4 hr) in the presence of melatonin (2.5 mm), superoxide dismutase (25 units/mL), catalase (200 units/mL) or glutathione (0.5 mm). The defined relative index (malondialdehyde levels/accumulated ALA) × 100, decreases with incubation time, reaching values of 76% for melatonin and showing that the different antioxidants tested can protect astrocytes against ALA‐promoted lipid peroxidation. Concerning porphyrin biosynthesis, no effect was observed with catalase and superoxide dismutase whereas increases of 57 and 87% were obtained with glutathione and melatonin, respectively, indicating that these antioxidants may prevent the oxidation of porphobilinogen deaminase, reactivating so that the AIP genetically reduced enzyme. Here we showed that ALA induces cell death displaying a pattern of necrosis. This pattern was revealed by loss of cell membrane integrity, marked nuclear swelling and double labeling with annexin V and propidium iodide. In addition, no caspase 3‐like activity was detected. These findings provide the first experimental evidence of the involvement of ALA‐promoted ROS in the damage of proteins related to porphyrin biosynthesis and the induction of necrotic cell death in astrocytes. Interestingly, melatonin decreases the number of enlarged nuclei and shows a protective effect on cellular morphology.
Obstructive apneas produce high negative intrathoracic pressure that imposes an afterload burden on the left ventricle. Such episodes might produce structural changes in the left ventricle over time. ...Doppler echocardiograms were obtained within 2 months of attended polysomnography. Patients were grouped according to apnea–hypopnea index (AHI): mild/no obstructive sleep apnea (OSA; AHI <15) and moderate/severe OSA (AHI ≥15). Mitral valve tenting height and area, left ventricular (LV) long and short axes, and LV end-diastolic volume were measured in addition to tissue Doppler parameters. Comparisons of measurements at baseline and follow-up between and within groups were obtained; correlations between absolute changes (Δ) in echocardiographic parameters were also performed. After a mean follow-up of 240 days mitral valve tenting height increased significantly (1.17 ± 0.12 to 1.28 ± 0.17 cm, p = 0.001) in moderate/severe OSA as did tenting area (2.30 ± 0.41 to 2.66 ± 0.60 cm2 , p = 0.0002); Δtenting height correlated with ΔLV end-diastolic volume (rho 0.43, p = 0.01) and Δtenting area (rho 0.35, p = 0.04). In patients with mild/no OSA there was no significant change in tenting height; there was a borderline significant increase in tenting area (2.20 ± 0.44 to 2.31 ± 0.43 cm2 , p = 0.05). Septal tissue Doppler early diastolic wave decreased (8.04 ± 2.49 to 7.10 ± 1.83 cm/s, p = 0.005) in subjects with moderate/severe OSA but not in in those with mild/no OSA. In conclusion, in patients with moderate/severe OSA, mitral valve tenting height and tenting area increase significantly over time. This appears to be related, at least in part, to changes in LV geometry.
Clinical prediction of portopulmonary hypertension (PPHTN) is critical in the preoperative evaluation of candidates for orthotopic liver transplantation (OLT) because of its association with ...significant morbidity and mortality. To determine the clinical, laboratory, and echocardiographic predictors of PPHTN, we retrospectively evaluated 55 candidates before OLT. From those, 8 candidates had pulmonary hypertension (HTN group A) and 47 candidates did not (group B). Pulmonary HTN was defined as a mean pulmonary artery pressure (PAP) of 25 mm Hg or greater and either elevated pulmonary vascular resistance or normal pulmonary artery wedge pressure. The significant predictors of PPHTN were (1) systemic arterial HTN (63% in group A v 9% in group B; P < .001), (2) loud pulmonary component of the second heart sound (38% v 2%; P = .001), (3) right ventricular (RV) heave (38% v 4%; P = .002), (4) RV dilatation by echocardiogram (63% v 0%; P < .001), (5) RV hypertrophy by echocardiogram (38% v 0%; P = .001), and (6) echocardiogram‐estimated systolic PAP (SPAP) greater than 40 mm Hg (63% v 2%; P < .001). The sensitivity of these variables for the detection of pulmonary HTN ranges from 37% to 63%, and their specificity from 91% to 100%. We conclude that several clinical and echocardiographic features are significantly associated with pulmonary HTN in patients with cirrhosis. In particular, echocardiogram‐estimated SPAP greater than 40 mm Hg is strongly associated with pulmonary HTN and is specific. These predictors, however, are not sensitive enough to identify all the patients with PPHTN. Therefore, the evaluation of a combination of these variables may be useful for the preoperative identification of pulmonary HTN in liver transplant candidates.
New indications for permanent cardiac pacing have been developed in recent years, with numerous studies demonstrating improved clinical outcomes in a variety of disorders. Because hypertrophic ...obstructive cardiomyopathy, dilated cardiomyopathy, heart failure, neurocardiogenic syncope, and atrial fibrillation are common conditions, every clinician should be aware of evolving alternative therapies for them. Observational studies in patients with refractory, symptomatic hypertrophic obstructive cardiomyopathy and significant left ventricular outflow gradient at rest suggest that cardiac pacing may result in symptomatic and hemodynamic improvement. Clinical trials have not shown conclusive evidence regarding the long-term benefit from pacing in these patients, and it is unclear whether pacing will be a preferred treatment option. Preliminary data suggest that pacing is a viable adjunctive therapeutic approach for improving symptoms in patients with dilated cardiomyopathy and heart failure. Mortality benefit has yet to be established, but it is to be hoped that ongoing randomized clinical trials will provide definitive information on that issue. Patients with refractory neurocardiogenic syncope or those who are intolerant of medical treatment may benefit from pacing therapies, especially those that use rate-drop sensor algorithms. Biatrial pacing has emerged as a technique that resynchronizes atrial electrical activity and has been shown to prevent atrial fibrillation. Multisite atrial pacing for the prevention of atrial fibrillation is considered investigational but seems promising. Newer indications for pacing are expected to result in improved clinical outcomes for hypertrophic obstructive cardiomyopathy, dilated cardiomyopathy and heart failure, neurocardiogenic syncope, and the prevention of atrial fibrillation.
Penetrating atherosclerotic aortic ulcers Movsowitz, H D; Lampert, C; Jacobs, L E ...
The American heart journal,
12/1994, Letnik:
128, Številka:
6 Pt 1
Journal Article
Recenzirano
Penetrating atherosclerotic aortic ulceration is a unique disease with distinct management and prognostic implications. It is an important clinical entity that must be distinguished from classic ...aortic dissection and rapid expansion or contained rupture of a thoracic aortic aneurysm. Although symptoms of penetrating aortic ulceration may mimic dissection, the characteristic signs of dissection are absent. New imaging modalities have made it possible to establish the diagnosis of penetrating aortic ulceration with a high degree of accuracy and to tailor management according to the presence of complications. Physicians should be aware of the possibility of atherosclerotic aortic ulceration, particularly in elderly patients with systemic atherosclerosis and hypertension who have sudden onset of chest or back pain.
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