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Biomedical subjects

Y H Li

Publications and source records attributed to Y H Li.

At least 145 records · Page 8Linked to original sources
PubMed1995

Mitral valve aneurysm and infective endocarditis: report of four cases.

From March 1992 to March 1994, four cases of mitral valve aneurysm were diagnosed at National Taiwan University Hospital. Mitral valve infective endocarditis was documented in three patients, while aortic valve infective endocarditis was found in the other. The diagnosis of mitral valve aneurysm was based on characteristic echocardiographic findings. The mitral valve aneurysms in these four cases were all visualized by transesophageal but not transthoracic echocardiography. At the time of diagnosis, three patients with a history of mitral valve endocarditis had perforated mitral valve aneurysms and severe mitral regurgitation. Although not found before surgery, the remaining patient with a history of aortic valve endocarditis was noted to have an unperforated mitral valve aneurysm one month after aortic valve replacement. All three patients with severe mitral regurgitation underwent mitral valve replacement and the patient with an unperforated mitral valve aneurysm was managed conservatively and obtained a stable clinical condition. In conclusion, mitral valve aneurysm usually appears to be associated with infective endocarditis and transesophageal echocardiography is more helpful in the diagnosis of mitral valve aneurysm than transthoracic echocardiography. Furthermore, unperforated mitral valve aneurysms may be managed conservatively with careful follow-up.

Adult↗
PubMed1995

Single giant ectopic ureter: report of two cases.

Two cases of unilateral single giant ectopic ureter are reported. In each case the child had complained of mild urinary symptoms since early childhood, but these had not been investigated. Routine physical examination revealed a palpable mass in the abdomen. Imaging studies revealed absence of the kidney on one side, with hypertrophy of the contralateral kidney and a giant tubular ureter extending from the upper abdomen to the lower abdomen behind the bladder, indenting the bladder wall and terminating at the posterior urethra. The ureters measured more than 8 cm in diameter in most parts. In both cases the giant ectopic ureters were successfully removed.

Child↗
PubMed1994

Clinical implications of left atrial appendage function: its influence on thrombus formation.

This study evaluated the relation between left atrial appendage (LAA) function and LAA spontaneous echo contrast (SEC) or thrombus formation. Seventy-five patients (45 men and 30 women, aged 14-79 years) referred for transesophageal echocardiography (TEE) were examined for LAA area (maximal and minimal), LAA ejection fraction ([LAA maximal area--LAA minimal area]/LAA maximal area), LAA peak emptying velocity, and these patients were classified into three groups by different LAA blood flow patterns: Group 1--25 patients with well-defined biphasic configuration of LAA flow; Group 2--28 patients with multiphasic configuration of LAA flow; Group 3--22 patients with very low LAA blood flow and, sometimes, barely detected Doppler signal. All the 25 patients in Group 1 had a sinus rhythm during TEE study, while the other 50 patients in Groups 2 and 3 were in atrial fibrillation. The patients in Group 3 had the lowest LAA ejection fraction and the lowest peak emptying velocity of these three groups. LAA SEC was present in five of 28 patients in Group 2 and 14 of 22 patients in Group 3, but in none of 25 patients in Group 1 (P < 0.001). LAA thrombus was present in one of 25 patients in Group 1, two of 28 patients in Group 2, and seven of 22 patients in Group 3 (P < 0.05). In conclusion, this study found that patients with poor LAA function, which was represented by lower LAA ejection fraction and lower peak emptying velocity, had higher incidence of LAA SEC or thrombus formation.

Adolescent↗
PubMed1994

Characteristics of accumulation of oral gram-positive bacteria on mucin-conditioned glass surfaces in a model system.

Strains of Streptococcus, Actinomyces and Lactobacillus were grown on glass surfaces in semi-defined medium (pH 7.0) with mucin, at a dilution rate of D = 0.1 h-1, in a modified chemostat. The accumulation of cells followed four phases. In phase 1 (0-1 h), cells did not divide on the surfaces and adhesion accounted for rapid accumulation. Phase 2 (1-4 h) comprised adhesion and cell division, and accumulation slowed, cell number doubling times (Cdt) Streptococcus, 2.7 h to 8.6 h, Actinomyces, 2.3 h to 7.5 h and Lactobacillus, 3.6 h to 3.8 h. Cell division on surfaces accounted for accumulation in phase 3 (4 h to 12 h): Cdt Streptococcus, 1.7 h to 5.2 h, Actinomyces, 2.4 h to 7.5 h and Lactobacillus, 2.2 h to 7.2 h. The biofilm stabilized in Phase 4, Cdt 18.5 h to 90.2 h. The numbers (10(6) colony-forming units per cm2) of cells in stable biofilms were Streptococcus, 4.02 to 5.12, Actinomyces, 12.5 and 34.0 and Lactobacillus, 2.77. Accumulation increased (Cdt 0.9 h-2.7 h) when cells were exposed to glucose excess or high dilution rates and phase 2 of accumulation did not occur.

Actinomyces↗
PubMed1994

Hazardous chemicals: psychological dimensions of the health sequelae of a community exposure in Texas.

STUDY OBJECTIVE: A chemical spill from an oil refinery exposed the local community to more than 40,000 lb of highly toxic and corrosive hydrofluoric acid. A community based symptom prevalence study found an association between exposure and physical symptoms: the psychological impact of the disaster and its potential effect on the reporting of physical symptoms is examined here. DESIGN: The study used a population based survey design consisting of two phases: phase I, the exposure phase, and, phase II, the symptom prevalence phase. SUBJECTS: In phase I, information indicative of exposure was collected on 10,811 individuals in a door to door survey of a geographically defined area. In phase II, symptom prevalence information was gathered through in-person interviews with 2509 subjects selected from the phase I census in a sampling scheme that balanced across the exposure categories with regard to age, gender, and predisposition. The refusal rate in both phases was < 5%. MEASUREMENT AND MAIN RESULTS: Stepwise logistic regression analyses were used to assess the relative predictive importance of psychological variables and hydrofluoric acid exposure in explaining the reported physical symptoms two years after the disaster. The findings show a linear relationship between the level of hydrofluoric acid exposure and the degree of psychological stress two years after the accident. High exposure had a long term (more than two years) impact on physical health for some self reported symptoms, even after controlling for the psychological impact. Some physical symptom reports, however, were better explained by psychological status than by exposure to hydrofluoric acid. The physical symptoms for which exposure was the major predictor were those for which the biological plausibility of a relationship with hydrofluoric acid exposure was direct. CONCLUSIONS: Measures of psychological status should be included in symptom studies of health sequelae to man-made disasters so that the physical effects of exposure can be more accurately assessed.

Adolescent↗
PubMed1994

Clinical implications and factors related to left atrial spontaneous echo contrast in chronic nonvalvular atrial fibrillation.

The mechanisms leading to formation of spontaneous echo contrast (SEC), a smoke-like echo on echocardiography, are still controversial. To further explore the clinical implications and factors related to SEC formation, the correlation among echocardiographic variables, hematologic parameters or platelet aggregability, and the occurrence of SEC was studied in 119 patients with chronic nonvalvular atrial fibrillation. There were 75 men and 44 women with a mean age of 65 +/- 10 years (range 38-88). Left atrial SEC was detected in 39 patients (33%) by transesophageal echocardiography. Patients with history of systemic embolism were more frequently found to have left atrial SEC and left atrial thrombus by univariate analysis. Multivariate analysis showed that left atrial SEC (p < 0.001) was the only independent predictor of history of systemic embolism. Age, sex, left atrial or left ventricular dimension, left ventricular ejection fraction, antiplatelet or anticoagulant therapy and the percentage of lone atrial fibrillation were not significantly different between patients with and without left atrial SEC. Among the hematologic parameters, higher hematocrit was found in patients with left atrial SEC, while white blood cell and platelet counts were comparable in both groups. Platelet aggregability with different concentrations of inducers, adenosine diphosphate and collagen, was evaluated by the turbidimetric method in 15 patients with left atrial SEC and in 42 patients without left atrial SEC who were not receiving antiplatelet or anticoagulant therapy. No significant difference was found in platelet aggregability using four inducer concentrations between two groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Left atrial appendage function determined by transesophageal echocardiography in patients with rheumatic mitral valve disease.

Left atrial thrombi have been considered to be the major source of systemic arterial embolization in patients with rheumatic mitral valve disease. Almost half of the left atrial thrombi are found in the left atrial appendage (LAA). To investigate LAA size and LAA contractile function in patients with rheumatic mitral valve disease, transesophageal echocardiographic and Doppler studies were performed in 61 patients. Among them, 46 patients were in atrial fibrillation (group 1), while the other 15 were in sinus rhythm (group 2). Thirty-six patients with nonrheumatic atrial fibrillation were chosen as control to group 1. Another 22 patients with various cardiovascular diseases and sinus rhythm served as control to group 2. When compared to the patients with nonrheumatic atrial fibrillation (control group), group 1 patients tended to have a larger LAA maximal area (9.7 +/- 5.2 vs. 5.9 +/- 2.8 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were also lower. A significantly higher incidence of LAA spontaneous echo contrast (SEC) and thrombus formation was also found in these patients. Group 2 patients were also found to have a larger LAA maximal area when compared to the control group (8.8 +/- 3.7 vs. 5.2 +/- 3.0 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were lower in this group, too. A higher incidence of LAA SEC formation was found in these patients with rheumatic mitral valve disease (4/15 vs. 0/22; p = 0.021). There was no significant difference, however, in LAA thrombus formation between group 2 and its control group (1/15 vs. 1/22; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The effect of environmental pH and fluoride from the substratum on the development of biofilms of selected oral bacteria.

The present study was initiated to answer the question, "Does fluoride from the substratum influence the accumulation of bacterial cells in an associated biofilm?" 'Fluoride-bound hydroxyapatite' (FHA) and 'fluoride-free hydroxyapatite' (HA) rods were prepared as test and control surfaces, respectively. Biofilms of S. mutans BM71, A. naeslundii genospecies 2 WVU627, and L. casei BM225 accumulated on the surfaces of rods in a semi-defined, mucin-based medium in a chemostat. Culture conditions were varied from pH 4.5 to 7.0 under carbon (glucose) limitation and excess, at a dilution rate of D = 0.1 h-1. Low environmental pH reduced both the numbers of cells on HA surfaces during the early phases (from 0 to 2 h) of accumulation and the final numbers of cells in mature biofilms (20 h). The initial adherence of cells was unaffected by surface fluoride under any of the conditions tested. Similarly, biofilm cells under carbon limitation and those under carbon excess at pH 7.0 were not affected by surface fluoride. However, at low environmental pH values, pH 5.5 for S. mutans and pH 6.0 for A. naeslundii under glucose excess, the accumulation of biofilm cells on the FHA surfaces was significantly reduced (p < 0.05-0.001). Biofilm cell number doubling times of S. mutans and A. naeslundii were increased on FHA relative to HA. Biofilms of L. casei were not significantly affected, even at pH 4.5 in glucose excess. The results confirmed that fluoride from the substratum affected fluoride-sensitive biofilm cells but only under conditions of glucose excess ad low pH.

Actinomyces↗
PubMed1994

Clinical implications of left atrial appendage flow patterns in nonrheumatic atrial fibrillation.

Left atrial appendage (LAA) function and flow patterns in 29 patients with chronic nonrheumatic atrial fibrillation were studied by transesophageal echocardiography. These 29 patients (16 men and 13 women; mean age, 63.8 years; range, 38 to 77 years) were classified into two groups according to different LAA flow patterns. Seventeen patients (group 1) had well-defined LAA emptying and filling Doppler flow signals, and the other 12 patients (group 2) had very low LAA flow signals. No significant differences were found in age, sex, mean duration of atrial fibrillation, left ventricular end diastolic dimension, and left ventricular ejection fraction between the two groups. However, group 2 patients had larger left atrial diameter (42.8 +/- 4.2 mm vs 36.6 +/- 8.8 mm; p < 0.05), lower LAA ejection fraction (26.4 +/- 15.2 percent vs 42.6 +/- 14.1 percent; p < 0.05), and lower LAA peak emptying velocity (0.13 +/- 0.03 m/s vs 0.36 +/- 0.16 m/s; p < 0.001). Higher incidence of LAA spontaneous echocardiographic contrast formation in group 2 patients (8/12 vs 1/17; p < 0.001) was noted. In conclusion, a subset of patients with nonrheumatic atrial fibrillation were found to have lower LAA blood flow and poorer LAA function. These patients had higher incidence of left atrial or LAA spontaneous echo contrast formation which had been proved previously to be a marker for future systemic thromboembolism.

Atrial Fibrillation↗
PubMed1994

Renal hypoplasia, Gartner's duct cyst and imperforated hemivagina: report of a case.

A girl with unilateral renal hypoplasia, ipsilateral Gartner's duct cyst and ipsilateral imperforate hemivagina is reported. She had a history of urinary drib-bling since early childhood. Recently, a foul bloody vaginal discharge was noted. Diagnosis was highly suspected on pelvic sonography, computerized tomography and magnetic resonance imaging, and was confirmed by punctures in the genitourinary tract with contrast study during surgery. This anomaly is extremely rare. Although three patients with similar conditions have been previously reported, different clinical presentations were noted in this patient.

Abnormalities, Multiple↗
PubMed1994

[Effects of wuzi yanzong pills on lipid in rats with alcohol-induced liver injury].

Experiments showed that in the rat model of alcohol-induced liver injury, a dosage of the pills (1-2g/kg, ig) could increase the cholesterol level, lower the triglyceride level, and improve the fatty degeneration and necrosis of liver (P < 0.05-0.01). The results suggest that the important mechanism of the pills in protecting and treating alcoholic fatty liver, lies in the regulation of metabolism of the lipid, especially of the triglyceride.

Animals↗
PubMed1993

Usefulness of pulmonary venous flow pattern and maximal mosaic jet area detected by transesophageal echocardiography in assessing the severity of mitral regurgitation.

Pulmonary venous flow pattern detected by transesophageal echocardiography (TEE) has been reported to be a good marker of mitral regurgitation (MR) severity. In 89 patients with MR detected by TEE, both pulmonary venous flow pattern and maximal mosaic jet area were recorded for evaluating the severity of MR. Cardiac catheterization was performed in all patients for grading the severity of MR. Systolic reversed flow in pulmonary veins was a good marker for angiographic grade 3 or 4 MR with a sensitivity of 97% (33 of 34) and specificity of 95% (52 of 55). Maximal mosaic jet area had a good correlation with the grading of MR (r = 0.79). When a maximal mosaic jet area of > 6 cm2 was used to detect grade 3 or 4 MR, the sensitivity and specificity were lower than those of the systolic reversed flow (sensitivity 82 vs 97%, p = 0.073; specificity 80 vs 95%, p = 0.013). The accuracy of systolic reversed flow was not influenced by the cardiac rhythm or jet eccentricity. However, the sensitivity of maximal mosaic jet area was lower in patients with an eccentric jet than in patients with a central jet (67 vs 95%, p = 0.046). In conclusion, systolic reversed flow in pulmonary veins detected by TEE is better than the maximal mosaic jet area in detecting grade 3 or 4 MR, especially in patients with eccentric jet.

Adolescent↗
PubMed1993

Purification and characterization of a yeast DNA polymerase alpha complex with associated primase, 5'-->3' exonuclease, and DNA-dependent ATPase activities.

We have purified a multimeric form of yeast DNA polymerase alpha with DNA polymerase, primase, 5'-->3' exonuclease, and single-stranded (ss) DNA-dependent ATPase activities to near-homogeneity. The molecular mass of complex was 650 kDa with subunits ranging in sizes from 30 to 180 kDa. The alpha-subunit of the complex could be detected by DNA polymerase alpha antibody. No cross-reactivity of polypeptides within the complex was observed with antibodies directed against polymerase delta or epsilon. The multimeric polymerase alpha could be selectively inhibited by p-n-butylphenyl-dGTP (I50 of approximately 0.2 microM), p-n-butylanilino-dATP (I50 of 1.3 microM), and aphidicolin (I50 of 2.5 micrograms/mL). The complex synthesized RNA primers on various ssDNA templates and rapidly elongated these primers into nascent DNA fragments in the presence of required deoxynucleotides. It has a strong 5'-->3' exonuclease activity. In addition, the complex hydrolyzed both ATP and dATP in a ssDNA-dependent manner. Thus, the multiprotein complex of DNA polymerase alpha had multiple activities (primase, polymerase, and ATPase) which could act concertedly to synthesize primers and elongate the primers to nascent DNA fragments in the lagging strand of the fork.

Adenosine Triphosphatases↗
PubMed1993

Expanded indication: diagnosis of pulmonary embolism by transesophageal echocardiography.

Transesophageal echocardiography is a useful diagnostic tool not only in examination of the heart, but also in examination of the great arteries. Its role in the diagnosis of aortic aneurysm and dissection has been well-established. The pulmonary artery, especially the right pulmonary artery, also can be visualized clearly by this technique. In this report, we described a patient with massive pulmonary embolism which was diagnosed by transesophageal echocardiography, and was confirmed by pulmonary angiography.

Adult↗
PubMed1993

Effects of human recombinant interleukin-1 on electrical properties of guinea pig ventricular cells.

OBJECTIVE: To determine whether cytokines alter the electrical properties of heart cells, the effects of human recombinant interleukin-1 beta (IL-1) were examined in excised tissues and dissociated myocytes from guinea pig ventricles. METHODS: In a first series of experiments, transmembrane potentials were recorded from isolated papillary muscles superfused with 1 ng.ml-1 IL-1 in the absence and presence of blockers of arachidonic acid metabolism. Secondly, to examine the ionic mechanisms underlying the response to IL-1, ventricular myocytes were dissociated from collagenase perfused hearts and studied using the whole cell configuration of the patch clamp technique under conditions designed to isolate the L-type Ca2+ current (ICa). RESULTS: In excised papillary muscles, IL-1 significantly prolonged action potential duration (measured at 90% repolarisation) by 24.2(SEM 2.2) ms and effective refractory period by 22.9(2.3) ms (both p < 0.001; n = 44). Other measured variables were not affected. Treatment of muscles with cyclo-oxygenase inhibitors, indomethacin (1 x 10(-5) M) or acetyl salicylic acid (2 x 10(-4) M), abolished the prolongation of action potential duration elicited by IL-1. However, the effects of IL-1 were also blocked by the lipoxygenase inhibitor nordihydroguaiaretic acid (2 x 10(-5) M) or by treating tissues with the leukotriene receptor blocker, ICI198615 (1 x 10(-8) M). In isolated myocytes, 1 ng.ml-1 IL-1 increased ICa density in 44 of 78 cells by 33.6(7.5)% [11.7(0.6) v 14.6(0.7) pA.pF-1; p < 0.001] during voltage steps from -40 to 0 mV. CONCLUSIONS: IL-1 modifies electrical properties of cardiac cells via lipid second messengers generated by cyclo-oxygenase and lipoxygenase pathways. Voltage clamp analyses suggest that these effects are mediated, at least in part, by changes in the conductance of calcium channels.

Action Potentials↗
PubMed1993

Acute myocardial infarction and left ventricular aneurysm in a patient with normal coronary arteries.

A 25-year-old young man was admitted with typical manifestations of acute myocardial infarction. Cardiac catheterization performed 2 weeks later showed a left ventricular aneurysm and normal coronary arteries. Because of the unusual clinical features, an endomyocardial biopsy was done and revealed histopathological changes of acute myocarditis. Acute myocarditis presenting as acute myocardial infarction with left ventricular aneurysm formation at the same time was never reported before. The long-term prognosis of the patient with left ventricular aneurysm caused by myocarditis still needs further observation.

Adult↗
PubMed1993

The psychological adjustment of the Chinese community in Britain. A study of two generations.

The psychological health and adjustment to life in Britain of a sample of first- and second-generation Chinese immigrants were measured. It was predicted that problems with the English language, inadequate social support, value differences, and unfulfilled expectations would induce more symptoms of psychological distress and depression in first-generation than in second-generation Chinese immigrants. Overall psychological health, and hence adjustment, was good. There was evidence for language problems and unfulfilled expectations, but not social support and value differences, being linked to mental health in the second generation. Evidence linking mental health to other personal variables was found in both generations.

Adaptation, Psychological↗