Application of mineral bed materials during fast pyrolysis of rice husk to improve water-soluble organics production.

Fast pyrolysis of rice husk was performed in a spout-fluid bed to produce water-soluble organics. The effects of mineral bed materials (red brick, calcite, limestone, and dolomite) on yield and quality of organics were evaluated with the help of principal component analysis (PCA). Compared to quartz sand, red brick, limestone, and dolomite increased the yield of the water-soluble organics by 6-55% and the heating value by 16-19%. The relative content of acetic acid was reduced by 23-43% with calcite, limestone and dolomite when compared with quartz sand. The results from PCA showed all minerals enhanced the ring-opening reactions of cellulose into furans and carbonyl compounds rather than into monomeric sugars. Moreover, calcite, limestone, and dolomite displayed the ability to catalyze the degradation of heavy compounds and the demethoxylation reaction of guaiacols into phenols. Minerals, especially limestone and dolomite, were beneficial to the production of water-soluble organics.

Design of a peptide inhibitor that blocks the cell fusion mediated by glycoprotein 41 of human immunodeficiency virus type 1.

Fusion between the envelope of HIV and the plasma membrane of target cells is mediated by gp41, the envelope glycoprotein of HIV. Peptides derived from the membrane-proximal helical motif of the extracellular domain of gp41 effectively inhibit the infection of HIV, and their inhibitory activities are known to be correlated with the helical propensity of the peptides. We have designed small peptides that can form a stable alpha helix and thereby inhibit gp120/41-mediated cell fusion. A 19-mer peptide from the membrane-proximal helical motif of gp41 had no secondary structure in solution, and failed to block gp41-mediated cell fusion. When amino acids with low helical propensity were substituted, and helix-capping sequences were introduced at both ends of the peptides, the modified peptides formed a stable helical structure. They also bound to the coiled-coil motif of gp41 presented at the C terminus of thioredoxin and blocked the cell fusion mediated by gp120/41. These results implied that such modification was enough to change a short peptide derived from gp41 into a potent inhibitor against the infection of HIV.

Two interaction modes of the gp41-derived peptides with gp41 and their correlation with antimembrane fusion activity.

Peptides derived from gp41 effectively block the gp41-mediated cell fusion or HIV infection. A 36-mer (naDP178), 51-mer (C51) and 27-mer peptide (C27) from the membrane proximal region of gp41 have been examined their interaction modes with the coiled-coil motif of gp41 presented in thioredoxin (Trx-N) or the bacterially expressed ectodomain of gp41 (Ec-gp41ec). All of these peptides effectively inhibited the gp41-mediated membrane fusion, however, they showed distinct interaction modes with Ec-gp41ec or Trx-N. C51 peptide bound tightly to Trx-N, and it increased the solubility of Ec-gp41ec. naDP178 showed very weak binding affinity to Trx-N, however, it effectively solubilized Ec-gp41ec. In contrast, C27 peptide showed significant binding to Trx-N; however, it did not affect the solubility of Ec-gp41ec. These interaction modes of C-peptides were assumed to be related to their different inhibitory mechanism against gp41-mediated cell fusion.

Assessment of intracardiac masses by transesophageal echocardiography.

Transesophageal echocardiography and 2-dimensional transthoracic echocardiography have proved to be extremely valuable in the diagnosis of cardiac masses. In this report, we review the echocardiographic findings, clinical history, and histopathologic findings in 21 patients with intracardiac masses who underwent transthoracic echocardiography, transesophageal echocardiography, or both, at our institution. Of these patients, 14 had benign masses and 7 had malignant tumors. The potential role of transesophageal echocardiography in the diagnosis and treatment of patients with intracardiac masses is discussed. We believe that transesophageal echocardiography offers the cardiologist and cardiovascular surgeon the capability of more accurate preoperative and intraoperative assessment of cardiac masses.

Successful thrombolysis for prosthetic pulmonary valve obstruction.

Thrombosis is a serious complication of prosthetic heart valve operations. In recent years, systemic thrombolysis has emerged as a suitable alternative to surgery. Experience with thrombosis of pulmonary prosthetic valves is very limited. We report a case of successful administration of intravenous streptokinase for thrombosis of a St. Jude Medical prosthetic valve 3 weeks after pulmonary valve replacement.

Flail tricuspid leaflet after multiple biopsies following orthotopic heart transplantation: echocardiographic and hemodynamic correlation.

Flail tricuspid leaflet has been reported as a relatively uncommon complication of endomyocardial biopsy in orthotopic heart transplant recipients. However, the relationship of this complication to the number of biopsies performed and to the site of access for biopsy is not known. The objectives of this study were to assess the prevalence of flail tricuspid leaflet/torn chordae tendineae in our recent transplant population, define the relationship of this complication to endomyocardial biopsy, and to correlate echocardiographic assessments of tricuspid regurgitation severity with hemodynamic data obtained at cardiac catheterization. From January 1991 to March 1993, 181 patients who had undergone orthotopic heart transplantation at our institution were evaluated with echocardiography for the presence of a flail leaflet or torn chordae tendineae of the tricuspid valve and tricuspid regurgitation. After identifying this complication in patients, we reviewed their hemodynamic tracings and biopsy protocols from the catheterization laboratory. The hemodynamic tracing chosen was that which was done at the time the flail leaflet was first diagnosed. Of the 181 patients, 21 (11.6%) had flail leaflet or torn chordae tendineae of the tricuspid valve. The group comprised 18 male and 3 female patients. The mean duration from the time of transplantation was 42 months (range, 1 to 87 months). The mean number of biopsies performed per patient was 15.5 (range, 2 to 27). The mean severity of tricuspid regurgitation by echocardiography was grade 3 (moderate); seven patients (33%) had severe regurgitation. The mean right atrial v wave by catheterization was 15 mm Hg (range, 6 to 26 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic evaluation of anuloplasty rings. Comparison of continuity equation and pressure half-time methods.

This study was undertaken to compare pressure half-time and continuity equation methods in the postoperative evaluation of anuloplasty rings. We performed 2-dimensional echocardiography and Doppler studies in 39 patients who had undergone valve repair for mitral regurgitation. In patients with a pressure half-time of 110 msec or more (9/39), there was no significant difference in calculated valve area between the 2 methods (p = 0.696). A significant difference was shown between the 2 methods (p < 0.001) in patients with a half-time less than 110 msec (30/39). When patients were classified according to the type of ring they had received, no significant difference was noted between the 2 groups with regard to peak and mean mitral gradients. In patients placed in subgroups according to half-times of less than 110 msec and half-times of 110 msec or more, no difference was noted between groups in terms of mean mitral gradient, presence of mitral regurgitation, left atrial size, left ventricular function, or heart rate. The continuity equation appears to provide much more homogeneous results in the calculation of valve area in patients who have undergone valvular repair for mitral valve regurgitation.

Doppler echocardiography in 180 normally functioning St. Jude Medical aortic valve prostheses. Early and late postoperative assessments.

Limited Doppler echocardiographic data are available regarding velocities and gradients across normally functioning St. Jude Medical valves in the aortic position. To establish a standard reference for Doppler characteristics of normal aortic St. Jude Medical prostheses, we recorded continuous-wave Doppler measurements of peak and mean velocities and peak and mean gradients in 180 patients with normally functioning St. Jude aortic valves. There were 119 men and 61 women in the study; the mean age was 57 years. Minimal valvular regurgitation was present in 56 patients (31 percent). Velocities and gradients were reported in five patient groups according to valve sizes of 19 mm, 21 mm, 23 mm, 25 mm, and 27 mm; the mean gradients were 16 +/- 6, 16 +/- 6, 14 +/- 5, 12 +/- 5, and 12 +/- 6, respectively. Differences in velocities and gradients among the five valve sizes were not statistically significant (p = 0.05). Velocities and gradients were also analyzed in three patient groups according to time intervals after valve replacement. The first group (n = 64) underwent Doppler evaluation one to seven days postoperatively (mean, six days); the second group (n = 60) was evaluated after 8 to 30 days postoperatively (mean, 12 days); and the third group (n = 56) was evaluated after more than 30 days postoperatively (mean, 691 days). There were no significant differences in measurements for the three groups.