A novel isoform of the smooth muscle cell differentiation marker smoothelin.

Studies on smooth muscle cell differentiation and those on vascular development in mouse and humans have long been hampered by the lack of suitable markers. Here we describe a novel, large isoform of smoothelin, a structural protein of differentiated, contractile smooth muscle cells. The protein, which is highly conserved in mouse and humans, shows homology with other cytoskeleton-associated smooth muscle cell proteins and contains an actinin-type actin-binding domain. Northern blot analysis from various mouse organs identified short and long smoothelin mRNA forms, which exhibit distinct tissue expression patterns. The short form is highly expressed in visceral muscle tissues such as intestine and stomach and is not detectable in brain, while the long mRNA form is expressed in all vascularized organs. These results may provide new tools and approaches to study both smooth muscle cell differentiation and proliferative vascular disease.

Infected left atrial myxoma with bacteremia simulating infective endocarditis.

A 58-year-old man had intermittent fever of eight months' duration following a dental extraction. There were no abnormal cardiac auscultatory findings. Multiple blood cultures yielded Streptococcus mutans. Treatment for infective endocarditis was initiated; however, an echocardiogram suggested the presence of a left atrial myxoma. The diagnosis was confirmed by angiography and the infected tumor was removed successfully. Differentiating features between left atrial myxoma and mitral valve endocarditis may not be obvious clinically, and bacteremia does not preclude atrial myxoma as a diagnostic possibility. We therefore suggest that all cases of infective endocarditis be evaluated by echocardiography to elucidate lesions such as large vegetations or left atrial myxoma, both of which may require urgent operative intervention.

Treatment of carotid artery stenosis by elective stent placement instead of carotid endarterectomy in patients with severe coronary artery disease.

Patients with concomitant cardiac and cerebrovascular disease undergoing revascularization procedures are at high risk of both, cardiac and cerebrovascular complications. The purpose of our study was to evaluate the feasibility of prior elective carotid artery stenting as an alternative treatment procedure to carotid endarterectomy (CEA) in patients with concomitant coronary artery disease (CAD), who clearly needed coronary revascularization. We offered extracranial internal carotid stenting to 85 patients with 89 significant carotid stenoses. Out of these, 19 patients were symptomatic. The quantitative mean reduction in diameter was 77 +/- 11%. Stent implantation was successful in 88 lesions. Two disabling major and 3 reversible minor strokes occurred periprocedurally. Three patients showed asymptomatic restenosis and stent deformation was detected in 2 patients. Based on this experience, carotid stenting in high risk patients with severe coronary artery disease is feasible and safe and might be indicated as an alternative procedure for combined surgery.

Relation between arteriosclerosis in the coronary and renal arteries.

This study analyzes the severity of coronary artery disease in terms of the severity of renal artery disease in 609 patients undergoing coronary and renal angiography. The presence of renal artery disease of any severity is strongly suggestive of advanced coronary artery disease.

Digital processing of contrast echocardiograms: a new technique for measuring right ventricular ejection fraction.

Imaging of the right ventricle with 2-dimensional echocardiography (2-D echo) is hampered by trabeculation of the right ventricular (RV) endocardial surface and by limited echocardiographic resolution. Determination of RV ejection fraction (EF) is thus often an inconsistent and tedious procedure. The process of digital subtraction contrast echocardiography was developed to maximize echocardiographic definition of the right ventricle and to assess RVEF with minimal operator interaction. Videotaped 2-D echocardiograms recorded during i.v. injection of agitated saline were digitized. Masks were constructed from end-systolic and end-diastolic apical 4-chamber and parasternal RV short-axis images. Masks were subtracted from corresponding images recorded with contrast in the right ventricle; images of the contrast alone were extracted and their areas determined. EF was calculated from raw area measurements and after conversion to volume. Comparison with RVEF measured by first-pass radionuclide angiography yielded the following correlation coefficients: 4-chamber RV area, r = 0.79; parasternal short-axis RV area, r = 0.59; ellipsoid approximation RV volume, r = 0.84; pyramidal RV volume, r = 0.79; and Simpson's rule triangular cylinder RV volume, r = 0.62. Digital subtraction contrast echocardiography is a new method that can be used for semiautomated determination of RVEF. Further studies to assess the clinical values of digital image processing of 2-D echocardiograms to measure RV function appear warranted.

Long-term severe pulmonary hypertension associated with right atrial myxoma.

An 18-year-old black woman presented with marginally compensated right heart failure, severe pulmonary hypertension, tricuspid incompetence, and right atrial myxoma. Catheterization suggested a substantial reactive component to her P-HTN, especially to nifedipine. Initial management consisted of excision of two right atrial myxomas and tricuspid annuloplasty, and postdischarge management with nifedipine, 30 mg four times daily. Emergency pulmonary thromboendarterectomy was required two weeks later for acute cor pulmonale. It is suggested that concomitant procedures are mandatory in this setting because of the otherwise accelerated adverse pathophysiology of obliterative pulmonary vascular obstructive disease.

Echocardiographic detection of an infected superior vena caval thrombus presenting as a right atrial mass.

A patient was found to have a large mobile right atrial mass by two-dimensional echocardiography after developing sepsis due to prolonged central hyperalimentation. Contrast echocardiography was helpful in localizing the origin of the mass. A large infected thrombus emanating from the superior vena cava was removed at operation. The discussion includes a review of the literature on the echocardiography of right atrial masses.

Mitral valve prolapse in the elderly.

This study included 40 patients over 60 years of age with echocardiographic findings of mitral valve prolapse (MVP). Most of these patients were unaware of any cardiac disorder until the time of echocardiography. In the majority, the clinical manifestations were benign, and the duration of symptoms variable. Congestive heart failure (CHF) was noted in 10 patients (25 percent) who were unaware of having any cardiac disorders until the onset of their symptoms. In 5 patients (4 with CHF and 1 with endocarditis), surgical replacement of the prolapsed mitral valve was necessary. Endocarditis was present in 4 patients (10 percent), none of whom had been instructed in the prophylactic use of antibiotics. The physician's awareness of mitral valve prolapse in the elderly patient is important, since the disorder may not be as benign in aged patients as in younger ones, and life-threatening complications may occur.

Assessment of echocardiographic left ventricular mass before and after acute volume depletion.

Left ventricular mass calculations are often performed to assess the need or effectiveness of antihypertensive drug therapy. However, there are multiple potential errors that may affect the accuracy of these calculations, which can possibly include acute changes in preload. Therefore, to assess the hypothesis that acute volume depletion might alter calculated left ventricular mass, 15 normotensive healthy male volunteers underwent standard M-mode echocardiographic evaluations (at the level of the chordae tendineae guided by two-dimensional echocardiography) before and 2 h after 40 mg of intravenous furosemide. One patient was eliminated due to hypotension prior to the final echocardiogram. The echocardiograms were blinded to patient identity and the time sequence and read separately by two investigators. Four to five cycles were read per echocardiogram by each investigator. All values measured were the mean of the two investigators. Echocardiographic measurements were derived by both the American Society of Echocardiography and Penn conventions. An average urine volume of 1728 mL was collected, and the mean weight change 2 h after furosemide administration was 1.78 kg (P = .001). Penn left ventricular diastolic diameter (1.8 mm, P = .015) and left ventricular mass index (10 g/m2, P = .04) were significantly decreased; however, there was no significant change in septal, posterior, or relative wall thicknesses. As it is unreasonable to believe that acute remodeling of the left ventricle resulted in a decline in left ventricular mass in 2 hours, it is concluded that acute volume changes resulted in a decrease in left ventricular mass measurement due to the influence of diastolic diameter on the calculation of cardiac mass.

Congenital absence of pericardium: an unusual cause of atypical angina.

Congenital defects of the pericardium are unusual. Patients may experience exertional chest pain, cardiac arrhythmias, syncope, sudden death, or incarceration of myocardium, or they may be entirely asymptomatic. We describe the case of a symptomatic pericardial herniation diagnosed by echocardiography and confirmed by cineangiography. Successful repair was accomplished using a polytetrafluoroethylene soft-tissue prosthesis.

Mitral valve prolapse and stroke: echocardiographic evidence for a missing causative link.

There is general acceptance of a causal connection between mitral valve prolapse and systemic embolic events. The precise mechanism, however, remains controversial, with current hypotheses favoring the embolization of thrombotic deposits from the abnormal mitral valve. It might be surmised that echocardiography could easily document the presence of such thrombi, but actually, this has never been reported previously. Described herein is a patient with a severe cerebrovascular accident in whom echocardiography clearly demonstrated a mass of high embolic potential attached directly to the prolapsing mitral valve leaflet.

Assessment of late potentials in patients with essential hypertension by the signal-averaged electrocardiogram with five year follow-up.

Both the Framingham and Manitoba Heart Studies have identified electrocardiographic left ventricular (LV) hypertrophy (LVH) as a risk factor for sudden cardiac death. Low amplitude ventricular late potentials in the terminal part of ventricular activation have been associated with sustained ventricular tachycardia and have identified those at risk for sudden cardiac death. Therefore, we prospectively examined 23 essential hypertensives without known symptomatic coronary heart disease by two-dimensional echocardiography and signal averaged electrocardiograms (SAECGs) for the detection of ventricular late potentials. The SAECG vector-magnitude complex measurements included the total duration of the complex (QRSd), the voltage in the last 40 ms (V40), and the duration of low amplitude signals < 40 microV in the terminal portion of the complex (LASd). Echocardiographic parameter means were: LV diastolic diameter = 46.0 +/- 4.5 mm, combined septal and posterior wall thickness = 23.3 +/- 4.2 mm, LV mass (Woythaler method) = 235.1 +/- 69.1 g, LV mass (Penn method) = 199.5 +/- 55.3 g and ejection fraction = 63.9 +/- 6.2%. SAECG measurement means were QRSd = 88.2 +/- 9.9 ms, V40 = 63.1 +/- 34.7 microV RMS, and LASd = 23.5 +/- 10.0 ms. No echocardiographic parameter correlated with SAECG duration; however, age correlated with QRSd (r = 0.48, P = 0.02). Posterior wall thickness (r = -0.43, P = 0.04), LV mass index (r = -0.44, P = 0.03) and LV mass/height (r = -0.49, P = 0.02) inversely correlated with LASd.(ABSTRACT TRUNCATED AT 250 WORDS)

Model for static lifting: relationship of loads on the spine and the knee.

An experimental study based on a trigonometric, anthropometric model, was conducted on thirty-five healthy subjects to determine the relationship between knee and back forces during symmetric sagittal plane lifting. Total joint reaction forces for the knee and the back, along with their compressive and shear components, were calculated for each subject, as a function of the knee, back and ankle angles. The shear component was significantly higher in females than in males; the compressive component was significantly higher in males. Strong inverse correlations were found between the back and the knee forces on all subjects. Strong correlations were also found between subject anthropometry and minimum and maximum joint reaction forces. The magnitudes of both back and knee joint reaction forces should be considered in recommending the lift type and position, based upon individual worker anthropometry, and size and weight of the load to be lifted.

Case report: acute presentation of pseudo myocardial infarction secondary to metastatic cancer.

Electrocardiographic ST segment changes that mimic myocardial infarction (MI) may occur secondary to metastatic carcinoma. Presented here is a case in which symptomatology suggestive of acute MI occurred with impressive new anterior ST segment elevation in a patient with a history of laryngeal carcinoma. Clinical options in this setting are discussed, including use of thrombolytic agents and acute catheterization.

Right atrial thrombus formation following central venous dialysis catheter placement.

Silicone rubber central venous dialysis catheters are used to provide vascular access in acute renal failure patients and in chronic dialysis patients in whom conventional vascular access cannot be achieved or maintained. The use of these catheters is not without hazard. The first reported case of right atrial thrombus formation associated with the use of a double lumen silicone rubber central hemodialysis catheter is described. This patient's course points out another potential complication of this type of vascular access and emphasizes the importance of removing such catheters in a timely fashion when they are no longer required for dialysis.

An Internet-based simulation model for nitrogen management in agricultural settings.

Complex chemical, physical, and biological processes mediate nitrogen (N) transformations and movement during agricultural production, making the optimization of fertilizer use and environmental protection exceedingly difficult. Various computer models have been developed to simulate the site-specific fate and transport of N resulting from different crop production scenarios, but these models are very complex and difficult to use for most farmers, consultants, and conservationists. In an effort to facilitate access and simplify the use of sophisticated models, the U.S. Department of Agriculture (USDA) has developed an Internet-based nitrogen analysis tool. Based on the Nitrate Leaching and Economic Analysis Package (NLEAP), the Web site allows a user to conduct multiyear N simulation modeling specific to a crop field. Servers handle much of the required data assembly and formatting, thus sparing the user"s resources. Model runs are executed on the servers and the results are transmitted to the user. This new tool is presented along with early implementation results.

Evaluation of an intelligent seat system.

This study was conducted to evaluate the effect of an intelligent seat system, a microprocessor-based interactive seat that automatically adjusts itself to fit a seated individual by making pressure-sensitive adjustments on its own. First, a standard American automobile seat ('baseline' seat) was assessed for comfort. Subjective ratings of comfort, pressure distribution and seated anthropometric measurements were recorded for 20 test subjects. These measurements were recorded while the subjects maintained a simulated driving position in a seat buck. The comfort scale was based on a rating of 1 to 10, with 1 corresponding to 'very poor' and 10 corresponding to 'very good.' Based on a nonlinear, multiple regression model that had been previously developed, the comfort rating of the seat was predicted based on the subjective ratings and the recorded values of 450 pressure measurements from 20 subjects. The predicted comfort value was 7.46 for the baseline seat. Following the baseline assessment, the intelligent seat system was installed into the standard American automobile seat. The objective and subjective assessments were then repeated for 17 subjects and the new predicted comfort rating was 8.06. A t-test performed on the subjective and objective measures indicated that this was a significant improvement in seat comfort. Overall, subjects felt the self-adjusting seat was more customized and more comfortable, providing a better fit.