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Biomedical subjects

S L Lin

Publications and source records attributed to S L Lin.

At least 127 records · Page 7Linked to original sources
PubMed1992

Tailgut cyst with carcinoid: a case report.

Tailgut cyst, an unusual presacral lesion, is lined by a variety of epithelial types including squamous, columnar, transitional and cuboidal epithelium. Disorganized fascicles of smooth muscle may be seen in the cystic wall. Tailgut cysts are usually multiloculated, and often afflict adult women. In rare cases, adenocarcinoma arises within the tailgut cyst. We present a carcinoid tumor developing from the tailgut cyst. The tumor cells grow in ribbon and festoon patterns and are positive for argyrophilic granules. Immunostains for neuron-specific enolase are also positive. Ultrastructurally, dense-core, membrane-bounded neurosecretory granules are present.

Adolescent↗
PubMed1992

Quantitative analysis of the coronary angiograms.

This was a two-step study performed to assess the validity of a computer system in the quantification of coronary arterial angiography (CAG). First, the in vitro study involved 10 aluminum tubes in different internal diameters but the same thickness which were pre-filled with 76% urograffin followed by cinefilm taking. Acquisition and digitization of the stop film was undertaken by a videocamera linking to a computer system. The internal diameters and mean gray levels of all tubes were measured to compare with the real diameters and areas. Second, the in vivo study calculated the percentage of stenosis by visual estimation, diameter measurement and gray level measurement by the computer system from 22 vessels in 13 coronary angiograms. The percentage of patency is the ratio of the diameter or gray level from stenotic region to that of normal region in the CAG. The calculated interobserver variability by visual estimation, diameter measurement and Mean gray level measurement were studied. Good correlation was found between measured diameters and true tube diameters (r = 0.99), and between gray level and tube areas (r = 0.94). The diameter measured by computer and the gray level had lower variability (4.0% and 5.7% respectively) than visual estimation (9.8%) did. Thus, the diameter and densitometric gray level measurements might have clinical implications to assess the coronary arterial stenosis from the coronary angiograms.

Aged↗
PubMed1991

Comparison of the effects of saccharide binding and crystallization on the zinc transition-metal site of concanavalin A.

The Zn site in concanavalin A solution was studied by X-ray absorption fine structure spectroscopy (XAFS) with and without the saccharide methyl alpha-D-glucoside (aMG) bound to the protein. No structural change occurs in the metal-binding site when the saccharide is bound to the protein. There is, however, evidence for structural change remote from the metal site. This is in contrast to the significant changes that we have previously found to occur in the near neighborhood of the Zn atom when an aqueous solution of Zn concanavalin A crystallizes. We propose a structural explanation of these facts based on the known crystal structure of concanavalin A.

Concanavalin A↗
PubMed1991

Role of the N- and C-terminal actin-binding domains of gelsolin in barbed filament end capping.

Gelsolin is a bivalent Ca(2+)-modulated actin-binding protein that severs, nucleates, and caps filaments. In order to gain a better understanding of the capping mechanism we have studied N- and C-terminal gelsolin fragments, 14NT and 41CT, each of which contains a single functional actin-binding site. The very tight binding measured between gelsolin and the barbed filament end requires gelsolin to greatly decrease the dissociation rate constant of the terminal actin from this end. A mechanism that could account for the observed decrease in dissociation is one in which gelsolin links two actin monomers so that they dissociate more slowly as a dimer. This cannot be the only mechanism, however, since, as shown here, 14NT and 41CT, fragments with single actin-binding sites, decrease the dissociation rate of the capped terminal actin molecule. The observations suggest that these fragments induce a conformational change in the actin monomer that either increases the affinity or alters the kinetics of the terminal actin-actin bond. The available data argue for strengthening of the terminal actin-actin bond.

Acrosome↗
PubMed1991

X-ray absorption fine structure investigation of the zinc transition metal binding site of Zn concanavalin A in solution and in the crystal.

We report details on measurements by the X-ray absorption fine structure (XAFS) technique of the conformational changes around the transition metal binding site (S1) of the protein concanavalin A induced by crystallization when that site is occupied by Zn. A change from hexa- to tetracoordination occurs at the S1 site on crystallization when the calcium-binding site (S2) is occupied by a calcium atom. When the S2 site is unoccupied, the Zn is pentacoordinated both in solution and in the crystal. The average distance to the coordination shell increases with coordination number as expected. Conformational changes are detected up to 4.5 A from the Zn, the limit of sensitivity of the XAFS technique. When the Zn is hexacoordinated, the ligands around the Zn, as determined by XAFS, are consistent with the crystal structure determination results of five oxygens and one nitrogen. The atom that is released in the tetracoordinated Zn. decreases to five is an oxygen atom, and, in addition, the nitrogen is released in the tetracoordinated Zn. Thus, when S2 is emptied, the protein gains a ligand about the Zn site in the crystal and loses one in solution. These results provide direct evidence that the protein conformation can be altered by the intermolecular forces of crystallization.

Binding Sites↗
PubMed1991

Frequency and severity of mitral regurgitation one year after balloon mitral valvuloplasty.

Mitral regurgitation (MR) was evaluated by Doppler echocardiography in 59 patients with mitral stenosis before, immediately after and 1 year after balloon mitral valvuloplasty (BMV). The severity of MR was graded on a scale from 1+ to 4+. Echocardiographic and hemodynamic variables were analyzed to study the potential factor(s) that might predict the long-term persistence of MR. Echocardiographic variables were mitral valve thickness and motion, subvalvular change, left atrial dimension, commissural calcification and effective balloon/mitral anular diameters. Hemodynamic variables were mitral pressure gradient, pulmonary arterial pressure, ejection fraction, mitral valve area index, age, gender and cardiac rhythm. Mitral valve area index increased from 0.9 +/- 0.5 to 1.5 +/- 0.8 cm2/m2 immediately after BMW, and to 1.4 +/- 0.3 cm2/m2 at 1 year follow-up (p less than 0.01). Immediately after BMV, MR grading did not change in 30 patients (51%), increased by 1+ in 23 patients (39%), by 2+ in 2 patients (3.3%) and by 3+ in 2 patients (3.3%), and decreased by 1+ in 2 others. At 1-year follow-up, only 1 patient with severe MR required valve replacement. Fifty-one patients (88%) had no change in the extent of MR (less than or equal to 1+) and 6 patients (10%) had a 1-grade decrease in their MR; only 1 patient had a 1-grade increase in MR. No clinical or hemodynamic variables or morphologic characteristics of the mitral valve could predict the development of significant MR after BMV. It is concluded that an increment in MR severity less than or equal to 2+ is frequently seen after BMV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Transesophageal color Doppler flow mapping of iatrogenic left-to-right interatrial shunting after percutaneous transluminal mitral valvotomy.

Characteristics of transesophageal color Doppler flow mapping of iatrogenic left-to-right interatrial shunts were assessed in 58 patients, 1 to 994 days after percutaneous transluminal mitral valvotomy. Transesophageal color Doppler flow mapping detected 22 cases of interatrial shunt whereas transthoracic two-dimensional echocardiography visualized only five interatrial septal defects. Five types of color Doppler flow patterns of interatrial shunts were found: type 1, a bluish jet passing through the interatrial septum into the right atrium with a small bluish proximal flow in the left atrium (50%); type 2, a bluish jet passing through the interatrial septum into the right atrium without a proximal flow (13.6%); type 3, a predominant bluish proximal flow in the left atrium passing through the interatrial septum with minimal flow entering into the right atrium (18.2%); type 4, an "en face" bluish jet in the right atrium (4.5%); and type 5, a "wall jet" with proximal flow adhering to and entering into the interatrial septum (13.6%). Oximetry demonstrated increased pulmonary-to-systemic flow ratio (range 1.07 to 3.32) in 11 patients (50%), which was significantly correlated with the maximal jet area derived from color Doppler flow mapping (r = 0.80, P = 0.001). Thus, transesophageal color Doppler flow mapping is useful in detection of left-to-right interatrial shunts after percutaneous transluminal mitral valvotomy, and recognition of the variable types of color flow mapping may further help identify these atypical interatrial shunts.

Adult↗
PubMed1991

Detection of acute myocardial infarction by evaluation of ultrasonic gray levels in dogs.

The study tested whether an experimental myocardial infarction can be detected from two-dimensional echocardiograms (2DE) by analysis of regional gray levels. The mid-left anterior descending coronary artery was ligated for 3 hours in 14 dogs (group 1) and for 5 hours in 6 dogs (group 2). 2DE were performed before, and after 3 and 5 hours of coronary artery ligation. The ultrasonic amplitude of the control and infarcted regions were obtained from digitized 2DE in the short axis view, at the mid-papillary muscle level. The mean gray levels (+/- SD) of the control and infarcted regions were compared during end-diastolic stop frames. After sacrifice, the hearts were cut into 1 cm thick slices and stained with 1% triphenyl tetrazolium chloride (TTC) solution. The myocardium was then studied by light microscopy. Computerized tomographic scans were also obtained in vitro from 3 hearts of both groups. There was no difference in mean gray levels of the control region during the experiments. However, in the region of wall motion abnormality (area of infarction), the mean gray levels increased from 49.9 +/- 3.5 (before ligation) to 62.0 +/- 7.4 (after 3 hours of ligation, p less than 0.005) in 10 group 1 dogs, but no differences were seen in mean gray levels (49.6 +/- 3.8 vs 50.4 +/- 4.0) in those without a myocardial infarction in 4 group 1 dogs; gray levels also increased from 50.4 +/- 2.9 (before ligation) to 58.6 +/- 6.1 (after 3 hours of ligation, p less than 0.05) and to 65.0 +/- 4.2 (after 5 hours of ligation, p less than 0.005) in group 2 dogs. The area of left ventricular asynergy corresponded precisely to the area of myocardial infarction, determined by both TTC staining and the computerized tomographic scans. The light microscopy of the infarcted area also demonstrated interstitial edema and polymorphonuclear cell infiltration.

Animals↗
PubMed1991

Artifact simulating ventricular and atrial arrhythmia.

We describe a patient whose electrocardiograms showed ventricular tachycardia and atrial flutter which could be reproduced by arm movements. Careful review of the initiation and termination of the arrhythmia, the relation of the arrhythmia to body motion, and the associated symptoms and signs may be helpful to differentiate artifact from true arrhythmia.

Arm↗
PubMed1991

Changes in T-lymphocyte subpopulations in patients splenectomized for trauma.

Surface markers of peripheral mononuclear cells, using a monoclonal antibody, were characterized, and the serum immunoglobulins (IgG, IgM, IgA) as well as complement proteins (C3, C4) were determined in 20 adult patients with splenectomy because of trauma. A similar analysis was performed on 20 healthy individuals and the results compared. The average interval from splenectomy to testing was two years. The percentages of total T-cells (CD3), T-helper cells (CD4), and T-suppressor cells (CD8) were reduced in all subjects the splenectomized, but the results were statistically significant only for the CD4 cells (p less than 0.01). The proportion of B-cells (OKB7) showed no difference in either group. However, the ratio of CD4/CD8 cells was significantly decreased in splenectomized subjects (p less than 0.05). Measurement of serum immunoglobulins (IgG, IgA, IgM) and complement proteins (C3, C4) revealed no significant differences between the two groups. These data suggest that healthy adults undergoing splenectomy for trauma have a specific and persistent immunological deficit. Our results suggest that a more cautious and conservative attitude toward the splenic trauma should be adopted.

Adolescent↗
PubMed1991

The frequency of patent foramen ovale in patients with ischemic stroke: a transesophageal echocardiographic study.

Transesophageal echocardiography has been described as superior to transthoracic echocardiography in the detection of patent foramen ovale (PFO). Utilizing both methods, we were able to determine the frequency of PFO in younger adult patients with ischemic stroke (patient group) and in age-matched control subjects (control group). Thirty-four patients under 55 years of age with cerebral or retinal ischemic attacks (mean age 39 years) and 40 controls (mean age 39 years) were studied. Transesophageal echocardiography detected a significantly higher frequency of PFO in the patient group (44%) than in the control group (18%, p less than 0.05). In comparison with transthoracic echocardiography, transesophageal echocardiography found a higher frequency of PFO in both the patient group (12% vs 44%, p less than 0.01) and the control group (3% vs 18%, p less than 0.05). All of the foramina proved to be patent by transthoracic echocardiography were also found by transesophageal echocardiography. The results suggest that transesophageal echocardiography is a sensitive method for demonstrating PFO. Paradoxical embolism through an interatrial communication (PFO) may be a possible cause of strokes in the young adult.

Adult↗
PubMed1991

Surgical resection of hepatocellular carcinoma in the cirrhotic liver.

A total of 80 patients with asymptomatic small hepatocellular carcinoma (HCC) associated with liver cirrhosis underwent a liver resection. The patients were divided into 4 groups according to the location of their tumor: group A (n = 9): left lateral segmentectomy or left hepatectomy, group B (n = 42): atypical partial hepatectomy on the lateral aspect of the right lobe, group C (n = 25): subsegmentectomy on either the anterior or the posterior surface of the right lobe, group D (n = 4): subsegmentectomy in the hilar area. There were two postoperative deaths (both in group D) and five cases of hospital mortality (1 case due to myocardial infarction in group C; 1 case due to bleeding esophageal varices in group B and 2 cases in group C; and 1 case due to fulminating hepatitis in group B). There was no any significant difference in tumor size, the preoperative serum bromosulfaphthalein retention rate or the postoperative peak serum conjugated bilirubin level among all the groups (p less than 0.05). The weights of the resected specimens were higher in groups A and B (259 +/- 58 g, 230 +/- 154 g) than in groups C and D (54 +/- 32 g, 37.5 +/- 15.0 g) (p less than 0.05). The amount of blood required for transfusion during surgery in group D (3,625 +/- 3,146 mL) was significantly greater than in the other three, groups (p less than 0.05); and was also greater in groups B and C (1,649 +/- 880 mL, 1,635 +/- 1,156 mL), than in group A (444 +/- 273 mL; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Determination of low levels of the stereoisomers of leucovorin and 5-methyltetrahydrofolate in plasma using a coupled chiral-achiral high-performance liquid chromatographic system with post-chiral column peak compression.

A method for the determination of low levels of the stereoisomers of leucovorin and 5-methyltetrahydrofolate has been developed and validated. The assay involved initial chromatography on a bovine serum albumin (BSA)-based high-performance liquid chromatography chiral stationary phase (CSP) followed by post-column peak compression and elution on two C18 columns. In this manner, the poor efficiency of the BSA-CSP was overcome and sub-microgram quantities of the target solutes could be detected. The BSA-CSP separated the leucovorin and 5-methyletrahydrofolate from interfering plasma components and from each other and achieved the stereochemical resolution of the diastereomeric (6S)-and (6R)-leucovorin. The eluent containing (6S)-leucovorin was directed onto one C18 column and the eluent containing (6R)-leucovorin and 5-methyltetrahydrofolate was directed onto the other. This was followed by sequential rapid gradient elution of the target compounds from the respective C18 columns. The method was validated for plasma levels ranging from 15 to 500 ng/ml and was able to detect leucovorin concentrations of as low as 5 ng/ml.

Animals↗
PubMed1990

Evidence from X-ray absorption fine structure spectroscopy for significant differences in the structure of concanavalin A in solution and in the crystal.

We have used X-ray absorption fine structure spectroscopy (XAFS) to study and compare the structure of concanavalin A in crystals and in aqueous solution. Significant differences were found between crystal and solution in the configuration of the transition-metal site of the protein. The metal has six ligands in solution but only five in the crystal. The ligand bond lengths are shorter in the crystal than in solution. The vibrational disorder in the crystal and possibly the corresponding bond length show a negative temperature dependence whereas in solution they vary normally with temperature. The anomalous temperature dependence in the crystal suggests that as the temperature decreases the protein molecules are subject to additional stresses, which are transmitted as a tensile stress at the metal site leading to distorted geometry and lengthening and weakening of metal-ligand bonds.

Calcium↗
PubMed1990

Correlation of orbital computed tomography and antibodies in patients with hyperthyroid Graves' disease.

The purpose of this study was to elucidate the incidence of orbital changes in computed tomography, and the relationships of orbital changes with eye-muscle antibody (EMAb), thyrotrophin-binding inhibitor immunoglobulin (TBII), antithyroglobulin antibody (TgAb) and anti-thyroid microsomal antibody (MsAb), in 55 consecutive patients with hyperthyroid Graves' disease. EMAb was demonstrated by an immunoperoxidase technique. The results showed that the prevalence of orbital fat increase, extraocular muscle enlargement, lacrimal gland enlargement and optic nerve swelling were 54.5, 41.8, 21.8 and 16.5% respectively. There were 32.7% of patients without any orbital changes. The patients with extraocular muscle enlargement, lacrimal gland enlargement and optic nerve swelling had higher titres of EMAb than the patients without these orbital changes. The patients with lacrimal gland enlargement had a lower TBII index than those without. There was no difference in TgAb or MsAb between the patients with extraocular muscle enlargement, lacrimal gland enlargement, optic nerve swelling or orbital fat increase and those patients without these orbital changes. The patients with extraocular muscle enlargement, optic nerve swelling and orbital fat increase had a higher degree of exophthalmos than the patients without these orbital changes. EMAb was negatively correlated with TBII. However, there was no correlation between EMAb and TgAb or MsAb. The degree of exophthalmos was positively correlated with EMAb and negatively correlated with age. There was no correlation between exophthalmos and TBII, TgAb or MsAb. In conclusion, although the pathogenesis of orbital changes and hyperthyroidism is different, a close link between these two entities is suggested by the high incidence of orbital changes in hyperthyroid Graves' disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Usefulness of echocardiography in the prediction of early results of catheter balloon mitral valvuloplasty.

Catheter balloon mitral valvuloplasty (BMV) was performed in 50 patients and 32 of them undergoing BMV with double balloon technique were studied to evaluate the usefulness of echocardiography in the prediction of early results of BMV. Five echocardiographic variables including mitral valve motion, mitral valve thickness, subvalvular change, commissural calcification and left atrial dimension were evaluated. Each variable was divided into mild, moderate and severe subgroups. Before valvuloplasty there were no differences in mitral valve area among any subgroup for any variable. After valvuloplasty, variables associated with a greater increase in mitral valve area from mild and moderate subgroups than from severe subgroup included mitral valve motion, mitral valve thickness, and subvalvular change, but not commissural calcification or left atrial dimension. We scored the former 3 variables as 0, 1 and 2 points in the mild, moderate and severe subgroups, respectively. The sums of individual scores in these 3 variables were further divided into 3 groups: 12 patients had a lower score (less than 2), 10 patients had a score of 3-4 and 10 patients had a higher score (greater than 5). Patients with lower scores tended to have greater increases in mitral valve areas after valvuloplasty than those with higher scores. Thus, mitral valve motion, mitral valve thickness and subvalvular change may be useful to predict a greater increase in mitral valve area after valvuloplasty. A lower score of echocardiographic variables anticipates successful balloon mitral valvuloplasty, which may be helpful in patient selection.

Adult↗
PubMed1990

[Cavernous hemangioma of the heart: report of a case].

Cavernous hemangioma of the heart is a very rare disease. A 57-year-old male patient was admitted due to frequent onset of dull chest pain, which had been occurring for about 1 year. The pain was not related to exercise and was not relieved with nitroglycerin. On echocardiographic examination, a tumor was shown in the outflow tract of the right ventricle and was confirmed with computer tomography. He underwent open heart surgery for resection of the tumor. After a median sternotomy and opening of the pericardial cavity, a reddish-brown-colored tumor, 3 cm in diameter, was found protruding from the epicardial layer of the right ventricular outflow tract. The tumor involved all layers of the ventricle and could be resected only with the help of the cardiopulmonary bypass technique. The defect in the right ventricle was repaired with a woven dacron patch. The patient recovered without incident after the operation, and experienced no chest pain during 7 months of follow-up. Histology showed it to be a cavernous hemangioma.

Heart Neoplasms↗