High dislocation density-induced large ductility in deformed and partitioned steels

A wide variety of industrial applications require materials with high strength and ductility. Unfortunately, the strategies for increasing material strength, such as processing to create line defects (dislocations), tend to decrease ductility. We developed a strategy to circumvent this in inexpensive, medium manganese steel. Cold rolling followed by low-temperature tempering developed steel with metastable austenite grains embedded in a highly dislocated martensite matrix. This deformed and partitioned (D and P) process produced dislocation hardening but retained high ductility, both through the glide of intensive mobile dislocations and by allowing us to control martensitic transformation. The D and P strategy should apply to any other alloy with deformation-induced martensitic transformation and provides a pathway for the development of high-strength, high-ductility materials.

Twenty-year follow-up of the Carpentier-Edwards standard porcine bioprosthesis in the Oriental population

AIM

The 20-year period long-term results of porcine bioprosthetic valve use are limited. In addition, the majority of these reports come from Western countries. Given the scanty information reported in Oriental countries, this study was therefore designed to examine 20-year long-term results in patients who received a Carpentier-Edwards porcine bioprosthetic valve in an effort to contribute further information on the long-term clinical performance of porcine prosthetic valves from a viewpoint of results in the Oriental population.

METHODS

From July 1979 to April 2001, 82 patients received valve replacement with a standard Carpentier-Edwards porcine valve. There were 40 men and 42 women with a mean age of 42.3+/-15.1 years (range 16 to 73 years). Follow-up time extended more than 20 years (mean 10.9+/-3.2 years, range 0.5 to 21.5 years ) for a total of 719.5 patient-years.

RESULTS

The overall operative mortality was 16.9% (14 of 83 procedures). At 5, 10, 15, and 20 years, the actuarial survival rate of patients was 71.7%, 66.9%, 55.5%, and 44.4%, respectively. Actuarial estimates of freedom from structural valvular deterioration (SVD) at 5, 10, 15, and 17 years were 96.3%, 64.0%, 24.3%, and 24.3%, respectively; from reoperation 96.3%, 64.5%, 24.5%, and 24.5%; from operated valvular endocarditis 96.8%, 92.6%, 92.6%, and 92.6%; and from overall thromboembolism 96.3%, 88.5%, 67.2%, and 52.2%. In normal sinus rhythm, actuarial estimates of freedom from thromboembolism at 5, 10, 15, and 17 years were 100.0%, 100.0%, 81.8%, and 81.8%, respectively. Whereas for those in patients with atrial fibrillation, the estimates of freedom from thromboembolism were 94.5%, 82.4%, 57.7%, and 38.5%.

CONCLUSION

This study demonstrates the very satisfactory 20-year period long-term performance of freedom from bleeding events, thromboembolism (except in patients with atrial fibrillation), and valvular endocarditis in Oriental patients undergoing replacement with a porcine valve. However, the remarkable rate of SVD and reoperation ensued at 6 years after bioprosthesis implanted which does not differ from the series reported from Western countries.

Cystic left atrium myxoma--a rare case report

Myxoma is the most common primary tumor of heart. The typical picture of myxoma under echocardiography is a solid, dense echo mass and left atrium is the most common site to find it. The cystic form of myxoma is vary rare. We report a patient who received echocardiographic examination under impression of mitral valve stenosis. A multilobulated cystic mass which was like a hydatid cyst was found in the left atrium and atrioventricular flow was affected by this mass. After tumor resection, myxoma with internal hemorrhage was proved by pathology. No further recurrent myxoma was found during follow-up echocardiographic examination.

Effect of ionic and nonionic contrast media on fibrinolysis in patients undergoing angiocardiography

Very few investigators have studied the effect of contrast media on fibrinolysis. The results of those previous studies are contradictory and inconclusive. The purpose of this study was to evaluate the effect of ionic and nonionic contrast media on fibrinolysis in patients undergoing angiocardiography. Sixty-two patients randomly received either ionic contrast medium Hypaque-76 (n = 31) or nonionic contrast medium Ultravist-370 (n = 31). Plasma tissue plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), fibrinogen, and D-dimer were measured before and 20 minutes after the procedures. A significant increase of PAI-1 levels was seen in the Ultravist group but not in the Hypaque group. The t-PA and fibrinogen levels remained virtually unchanged in both groups. A significant increase of D-dimer concentrations was observed in the Hypaque group but not in the Ultravist group. The results of this study may in part explain the reason that the ionic contrast media produce fewer thromboembolic complications than the nonionic contrast media during the cardiac catheterization.

Atrioventricular block in Kearns-Sayre syndrome: a case report

The Kearns-Sayre (K-S) syndrome which includes the triad of progressive external ophthalmoplegia, pigment retinopathy, and disorder of cardiac conduction was first described in 1958. The mitochondria disorder is believed to be the cause of this syndrome. Involvement of the cardiac conduction system is the most importent prognostic factor in K-S syndrome. A 34-year-old male K-S syndrome patient, manifesting as ptosis and weakness of limbs since the age of 15 years, suffered from dizziness and weakness. Twelve-lead eletrocardiography (ECG) showed a 2:1 atrioventricular (AV) block with slow ventricular rate. Intermittent complete AV block, complete left bundle branch block and torsades de pointes were noted in Holter ECG. The electrophysiology study demonstrated prolonged HV interval (85 ms) on conduction beat and infra-His block on non-conduction beat. A VVIR mode of permanent pacemaker was implanted and the patient's condition was stable during this period of follow-up.

The effect of fluvastatin on fibrinolytic factors in patients with hypercholesterolemia

Several studies have shown cardiovascular benefit in treating hypercholesterolemia with HMG-CoA reductase inhibitor. However, in addition to the lowering of cholesterol, the beneficial effects of this inhibitor reflect other pharmacological activities. Whether these beneficial effects are partly mediated by changes in fibrinolytic factors remains to be proven, since clinical studies on the effects of HMG-CoA reductase inhibitors on fibrinolytic factors have not yielded consistent results. The purpose of this study was to evaluate the effects of fluvastatin on fibrinolytic factors in hypercholesterolemic patients. After 6 weeks on a low-fat, low-cholesterol diet, 23 outpatients known to have primary hypercholesterolemia with low density lipoprotein cholesterol (LDL-C) > or = 130 mg/dl with at least 2 risk factors or fasting LDL-C > or = 160 mg/dl were selected for the study. Venous blood samples were collected at baseline and at 8 weeks after fluvastatin therapy (40 mg/day) to measure of tissue plasminogen activator (t-PA), plasminogen activators inhibitor-1 (PAI-1), fibrinogen, D-dimer and lipid profile. After 8 weeks of therapy, fluvastatin reduced serum cholesterol by 11% (261.9 mg/dl vs 233.2 mg/dl, P < 0.01) and LDL-C by 22% (191.9 mg/dl vs 149.3 mg/dl, P < 0.01). D-dimer was significantly decreased (0.38 ng/L vs 0.28 ng/L, P = 0.02) and tPA, PAI-1 and fibrinogen tended to decrease after therapy. Fluvastatin therapy improved fibrinolytic profile; the result of this study may in part explain the benefit of HMG-CoA reductase inhibitor on cardiovascular system other than lipid lowering.

Human EZF, a Krüppel-like zinc finger protein, is expressed in vascular endothelial cells and contains transcriptional activation and repression domains

Members of the erythroid Krüppel-like factor (EKLF) multigene family contain three C-terminal zinc fingers, and they are typically expressed in a limited number of tissues. EKLF, the founding member, transactivates the beta-globin promoter by binding to the CACCC motif. EKLF is essential for expression of the beta-globin gene as demonstrated by gene deletion experiments in mice. Using a DNA probe from the zinc finger region of EKLF, we cloned a cDNA encoding a member of this family from a human vascular endothelial cell cDNA library. Sequence analysis indicated that our clone, hEZF, is the human homologue of the recently reported mouse EZF and GKLF. hEZF is a single-copy gene that maps to chromosome 9q31. By gel mobility shift analysis, purified recombinant hEZF protein bound specifically to a probe containing the CACCC core sequence. In co-transfection experiments, we found that sense but not antisense hEZF decreased the activity of a reporter plasmid containing the CACCC sequence upstream of the thymidine kinase promoter by 6-fold. In contrast, EKLF increased the activity of the reporter plasmid by 3-fold. By fusing hEZF to the DNA-binding domain of GAL4, we mapped a repression domain in hEZF to amino acids 181-388. We also found that amino acids 91-117 of hEZF confer an activation function on the GAL4 DNA-binding domain.

Double mycotic aneurysms of the ascending aorta

Infection in the vascular tree has been proved to be one of the greatest challenges for cardiovascular surgeons. Of these, mycotic aneurysms of the ascending aorta were considered to be almost always lethal until recently. A thorough survey of the literature indicates that only 42 cases of mycotic aneurysm of the ascending aorta have been reported. All the reported cases of mycotic aneurysm of the ascending aorta were a single lesion in the ascending aorta except a case reported in 1993. This report describes an additional case of double mycotic aneurysms of the ascending aorta caused by Pseudomonas infection.

The use of right gastroepiploic artery for the bypass of left anterior descending coronary artery--case reports

The right gastroepiploic artery (RGEA), a branch of the gastroduodenal artery, supplies the greater curvature of the stomach. It is capable of easily reaching the posterior and lateral surface of the heart as a reliable arterial conduit when appropriately harvested. In the previous reports, it has usually been anastomosed to the right coronary artery (RCA) or left circumflex coronary artery (LCX). Here, we present two cases of ischemic heart disease undergoing coronary revascularization. The RGEA was anastomosed to the left anterior decending coronary artery (LAD), which is the most important coronary artery in terms of patient outcome. Thallium-201 myocardial scintigraphy has proven that the RGEA can provide sufficient blood flow to the territory of the LAD. Thus, in coronary artery bypass grafting (CABG), the RGEA is a reliable arterial conduit for LAD revascularization.

Sick sinus syndrome with normal atropine response--a case report

A 76-year-old woman was admitted due to recurrent syncope. Sinus bradycardia and intermittent sinus pauses (up to 2.24 sec) were documented by 24 hour Holter electrocardiogram. Although intravenous atropine can increase the sinus rate up to 100 bpm, electrophysiologic study showed marked prolongation of sinus node recovery time both at the control state and after autonomic blockades. Sick sinus syndrome was diagnosed, even with a normal atropine test, and a permanent pacemaker resulted in resolution of the syncope.

Efficacy and safety of radiofrequency catheter ablation for paroxysmal supraventricular tachycardias

From January 1992 to June 1993, 100 consecutive patients with clinically documented paroxysmal supraventricular tachycardias underwent radiofrequency catheter ablation. Group 1 consisted of 46 patients (male:female = 9:37, age: 46 +/- 13 years) with slow-fast atrioventricular nodal reentrant tachycardia. Radiofrequency current was aimed at the slow pathway area which was identified by both anatomical and electrophysiological methods. A mean application of 8 +/- 9 was delivered at a mean power of 22 +/- 4 watts with a mean duration of 21 +/- 3 seconds. Selective ablation of slow pathway conduction was achieved in 28 patients and modification of slow pathway conduction in 12 patients. Antegrade fast pathway conduction was ablated in 3 patients, and retrograde fast pathway conduction in 1. Mean peak CPK was 156 +/- 117 IU/L after ablation. Neither AV block nor clinical recurrence was found during 9.7 +/- 5.1 months follow up. Group 2 consisted of 54 patients with accessory pathway (AP) mediated atrioventricular reciprocating tachycardia. For 35 patients (M:F = 21:14, age: 40 +/- 12 years) who had left-sided accessory pathway, catheter ablation was approached by the retrograde trans-aortic technique in 33 patients and by the transseptal left atrial approach through patent foramen ovale in 2 patients. The mean energy delivered was 28 +/- 5 watts for a duration of 27 +/- 12 sec and 9 +/- 8 applications. The accessory pathway conduction was successfully ablated in 30 patients (86%). Mean peak CPK was 392 +/- 534 IU/L. Cardiac tamponade occurred in 1 patient and transient cerebral ischemia in another, but without mortality. No clinical recurrence was found during 9 +/- 4 months follow-up. Nineteen patients (M:F = 7:12, age: 36 +/- 11 years) had right-sided AP. The mean energy required for successful ablation was 30 +/- 4 watts for a duration of 35 +/- 15 sec and 12 +/- 9 applications. Mean peak CPK was 147 +/- 70 IU/L. Clinical recurrence occurred in 3 patients (15.8%), 1 of them had subsequent successive ablation. The overall immediate procedure success rate for right-sided AP was 65%. In conclusion, radiofrequency catheter ablation is a safe and effective treatment modality for patients with paroxysmal supraventricular tachycardias.

The circadian variations of blood pressure and heart rate in patients with mitral valve prolapse

It is well known that both normal subjects and hypertensives manifest a distinct nocturnal fall of arterial blood pressure and heart rate. But till now there has been no report about the diurnal change of blood pressure and heart rate in MVP patients. In this report we studied the circadian variations of blood pressure and heart rate in 18 symptomatic MVP patients (mean age 32 +/- 10 years) and compared them with those in 18 age- and sex-matched normal control subjects (mean age 35 +/- 9 years). The MVP group presented a statistically significant blunting of the nocturnal fall in systolic blood pressure (4.2 +/- 3.6% vs 9.7 +/- 3.7%, p = 0.0002). No obvious difference in the nocturnal fall in heart rate was noted between both groups (20.2 +/- 6.0% vs 18.8 +/- 5.6%, p = 0.4290). In conclusion, the circadian variation of blood pressure was blunted in patients with mitral valve prolapse. The mechanism is uncertain and further studies are necessary to clarify it.

Cardiac amyloidosis--a case report

A 52-year-old male patient presented with resistant congestive heart failure. Echocardiographic findings revealed increased right ventricular (RV) wall thickness in conjunction with concentric left ventricular (LV) hypertrophy, LV systolic dysfunction and a granular sparking myocardial appearance. Doppler assessment showed a restrictive LV and RV diastolic filling pattern. These echocardiographic features combined with low voltage of the electrocardiogram is highly suggestive of cardiac amyloidosis. The diagnosis was confirmed by cardiac catheterization and endomyocardial biopsy.

Effect of ionic contrast medium on plasma atrial natriuretic peptide

To evaluate the effect of ionic contrast medium on plasma atrial natriuretic peptide (ANP) and its contributing factors, we measured plasma ANP, serum osmolality, pulmonary capillary wedge pressure (PCWP), femoral artery systolic pressure (FASP), and heart rate before and after left ventriculography with Rayvist in 13 patients suspected of coronary artery disease. The control values of plasma ANP, serum osmolality, and PCWP were 20.3 +/- 5.1 pg/ml, 293.5 +/- 1.5 mosm/kg, 6.6 +/- 0.8 mm Hg, respectively. Rayvist produced a significant increase in plasma ANP, serum osmolality, and PCWP at 1 minute (26.0 +/- 6.3 pg/ml, p < 0.05; 300.7 +/- 1.9 mosm/Kg, p < 0.001; 10.7 +/- 1.3 mm Hg, p < 0.001) and 5 minutes (27.3 +/- 6.3 pg/ml, p < 0.01; 296.8 +/- 1.9 mosm/Kg, p < 0.001; 10.4 +/- 1.7 mm Hg, p < 0.01) post left ventriculography. The FASP decreased significantly at 1 minute, followed by an insignificant increase at 5 minutes. The heart rate increased significantly at 1 minute but no significant change was noted at 5 minutes. We conclude that plasma ANP increases significantly after left ventriculography with Rayvist and its response may be related to left ventricular filling pressure and serum osmolality, but not to FASP or heart rate.

Comparison of the electrophysiologic effects of oral sustained-release and intravenous verapamil in patients with paroxysmal supraventricular tachycardia

The electrophysiologic effects of intravenous verapamil (0.15 mg/kg) and oral sustained-release verapamil (verapamil-SR) (240 mg once daily for 7 days) were studied in 17 patients with paroxysmal supraventricular tachycardia (SVT). Ten patients had atrioventricular (AV) nodal reentrant tachycardia and 7 had AV reciprocating tachycardia involving an accessory AV pathway. Both preparations significantly prolonged anterograde effective refractory period of the AV node and depressed the retrograde AV nodal conduction system. The sinus cycle length, and atrial and ventricular effective refractory periods were prolonged after oral verapamil-SR. Furthermore, oral verapamil-SR depressed retrograde accessory pathway conduction which was not interfered with by intravenous verapamil. Intravenous verapamil and oral verapamil-SR prevented induction of sustained SVT in 12 of 17 (71%) and 10 of 17 (59%) patients, respectively. Follow-up study with oral verapamil-SR 240 mg once daily in 15 patients for 19 +/- 6 months revealed that among the 8 patients without induction of sustained SVT, 7 have been free of symptomatic arrhythmia; only 1 patient had occasional SVT attacks. For the 7 patients with induction of sustained SVT, 3 patients failed to respond to oral verapamil-SR, 1 patient became symptom free, and the remaining 3 patients had less frequent SVT attacks. Thus, immediate intravenous verapamil testing predicts the electrophysiologic results of oral verapamil-SR therapy, and oral verapamil-SR once daily may be used for long-term prophylaxis of SVT with better patient compliance.

Efficacy of once-daily lisinopril monotherapy in systemic hypertension

Lisinopril is a new, long-acting angiotensin-converting enzyme inhibitor formulated for once-daily treatment of hypertension. This study assessed the 24-h efficacy and tolerability of lisinopril in Chinese patients with mild to moderate hypertension of World Health Organization Stages I to II. A total of 30 patients aged 30 to 60 years (mean 47 +/- 9) entered a 2-week washout period. All patients had ambulatory diastolic blood pressure (BP) > 90 mmHg and were given active treatment with lisinopril for 4 to 7 weeks. The dose of lisinopril was titrated from 10 to 40 mg daily (at 8-9 A.M.). In each patient, 24-h ambulatory blood pressure (BP) monitoring (SpaceLabs 90202) was performed twice, once before and once following treatment. Mean 24-hour systolic/diastolic BPs after lisinopril were significantly decreased compared with baseline values (132 +/- 12/86 +/- 7 vs. 150 +/- 11/98 +/- 7 mmHg; p < 0.0005/0.0005). The average dose of lisinopril was 14.5 +/- 5 mg daily after a titration period of 5 weeks of treatment. Mean daytime (6 A.M. to 6 P.M.) BP decreased from 152 +/- 11/100 +/- 8 to 134 +/- 12/87 +/- 8 mmHg (p < 0.0005/0.0005) and nighttime (6 P.M. to 6 A.M.) BP from 147 +/- 14/95 +/- 9 to 128 +/- 14/83 +/- 8 mmHg (p < 0.0005/0.0005). BP reduction was more pronounced during the night. Before treatment, the circadian variation showed a peak BP at 11 A.M. and nadir at 3 P.M. After treatment, significant BP reduction (p < 0.0005/0.0005) was seen throughout the 24-h period.(ABSTRACT TRUNCATED AT 250 WORDS)

Planar Rowland spectrometer for fiber-optic wavelength demultiplexing

A planar Rowland spectrometer was fabricated and characterized as a wavelength demultiplexer for multimode fiber-optic applications. The spectrometer consisted of a planar multimode glass waveguide with two curved end faces and a cylindrical concave grating attached to one of the end faces. Semiconductor lasers with wavelengths between 0.825 and 0.845 microm were used for the measurements. Cross-talk isolation between two adjacent fibers with center-to-center separation of 175 microm (100 A in wavelength difference) was measured to be 18 dB. The device's performance was limited by grating diffraction efficiency, optical aberration , waveguide dispersion, and waveguide losses.