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Biomedical subjects

K L Chan

Publications and source records attributed to K L Chan.

At least 217 records · Page 12Linked to original sources
PubMed1987

Marfan syndrome diagnosed in patients 32 years of age or older.

The Marfan syndrome, a generalized inherited disorder, is usually diagnosed in young patients and is associated with a poor prognosis. With use of our diagnostic-retrieval system, we identified 28 patients with the Marfan syndrome who were 32 years of age or older at the time of diagnosis. These patients had at least two of four major diagnostic criteria for the Marfan syndrome--a confirmed family history, a long-limbed habitus, dislocated lenses, and disease of the aortic root. In these relatively older patients, some clinical findings (the ocular disorder and the family history) corresponded to the expected findings in younger patients with the Marfan syndrome; however, the proportion of those with cardiovascular disease was greater. Echocardiography has improved the potential for detection of the cardiac lesions, the most frequent cause of death in these patients. Early diagnosis of the Marfan syndrome is important so that complications of the cardiac lesions can be prevented or delayed and so that genetic counseling can be done at an appropriate time.

Adult↗
PubMed1987

Comparison of three Doppler ultrasound methods in the prediction of pulmonary artery pressure.

Pulmonary artery pressure was noninvasively estimated by three Doppler echocardiographic methods in 50 consecutive patients undergoing cardiac catheterization. First, a systolic transtricuspid gradient was calculated from Doppler-detected tricuspid regurgitation; clinical jugular venous pressure or a fixed value of 14 mm Hg was added to yield systolic pulmonary artery pressure. Second, acceleration time from pulmonary flow analysis was used in a regression equation to derive mean pulmonary artery pressure. Third, right ventricular isovolumic relaxation time was calculated from Doppler-determined pulmonary valve closure and tricuspid valve opening; systolic pulmonary artery pressure was then derived from a nomogram. In 48 patients (96%) at least one of the methods could be employed. A tricuspid pressure gradient, obtained in 36 patients (72%), provided reliable prediction of systolic pulmonary artery pressure. The prediction was superior when 14 mm Hg rather than estimated jugular venous pressure was used to account for right atrial pressure. In 44 patients (88%), pulmonary flow was analyzed. Prediction of mean pulmonary artery pressure was unsatisfactory (r = 0.65) but improved (r = 0.85) when only patients with a heart rate between 60 and 100 beats/min were considered. The effect of correcting pulmonary flow indexes for heart rate was examined by correlating different flow indexes before and after correction for heart rate. There was a good correlation between corrected acceleration time and either systolic (r = -0.85) or mean (r = -0.83) pulmonary artery pressure. Because of a high incidence of arrhythmia, right ventricular relaxation time could be determined in only 11 patients (22%). Noninvasive prediction of pulmonary artery pressure is feasible in most patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Relative importance of antibiotic and improved clearance in topical treatment of chronic mucopurulent rhinosinusitis. A controlled study.

50 patients with chronic mucopurulent rhinosinusitis were randomly allocated to treatment with nasal sprays of dexamethasone, tramazoline, and neomycin, dexamethasone and tramazoline with no antibiotic, or matched placebo (propellant alone) four times daily to both nostrils for 2 weeks. The patients were assessed in a double-blind manner for symptomatic response and improvement in nasal mucociliary clearance, nasal airway resistance, sinus radiographs, and intranasal bacteriology and appearance. Both active preparations (with antibiotic 14 of 20 patients responded; without antibiotic 12 of 20 patients responded) were more effective than the placebo (2 of 10 patients responded). There was no significant difference in response between the active preparations with and without antibiotic. Thus, in treatment of chronic mucopurulent rhinosinusitis, reduction of the inflammatory response and decongestion make topical antibiotic unnecessary, probably by allowing host clearance mechanisms to recover.

Administration, Intranasal↗
PubMed1985

Continuous wave Doppler determination of right ventricular pressure: a simultaneous Doppler-catheterization study in 127 patients.

Simultaneous continuous wave Doppler echocardiography and right-sided cardiac pressure measurements were performed during cardiac catheterization in 127 patients. Tricuspid regurgitation was detected by the Doppler method in 117 patients and was of adequate quality to analyze in 111 patients. Maximal systolic pressure gradient between the right ventricle and right atrium was 11 to 136 mm Hg (mean 53 +/- 29) and simultaneously measured Doppler gradient was 9 to 127 mm Hg (mean 49 +/- 26); for these two measurements, r = 0.96 and SEE = 7 mm Hg. Right ventricular systolic pressure was estimated by three methods from the Doppler gradient. These were 1) Doppler gradient + mean jugular venous pressure; 2) using a regression equation derived from the first 63 patients (Group 1); and 3) Doppler gradient + 10. These methods were tested on the remaining 48 patients with Doppler-analyzable tricuspid regurgitation (Group 2). The correlation between Doppler-estimated and catheter-measured right ventricular systolic pressure was similar using all three methods; however, the regression equation produced a significantly better estimate (p less than 0.05). Use of continuous wave Doppler blood flow velocity of tricuspid regurgitation permitted determination of the systolic pressure gradient across the tricuspid valve and the right ventricular systolic pressure. This noninvasive technique yielded information comparable with that obtained at catheterization. Approximately 80% of patients with increased and 57% with normal right ventricular pressure had analyzable Doppler tricuspid regurgitant velocities that could be used to accurately predict right ventricular systolic pressure.

Adolescent↗
PubMed1984

Coronary thrombosis and subsequent lysis after a marathon.

A patient who developed an acute anterior myocardial infarction after completion of a marathon is presented. Coronary angiography performed 5 hours after the onset of symptoms showed occlusion of the left anterior descending coronary artery and nonocclusive thrombus in the proximal right coronary artery. Repeat angiography 10 days later showed complete resolution of thrombosis in both arteries. The relation between marathon running and coronary thrombosis is discussed.

Adult↗
PubMed1980

Multiple phosphoglucomutase alleles in Toxorhynchites splendens (Diptera: Culcidae).

Multiple phosphoglucomutase (E.C. 2.7.5.1) alleles are found in the mosquito Toxorhynchites splendens. The sample studied reveals 3 Pgm alleles whose frequencies are in good accord with Hardy-Weinberg expectations. The most frequent allele is that controlling a phenotype with an intermediate electrophoretic mobility. Each Pgm allele determines a two-band electrophoretic pattern.

Alleles↗
PubMed1980

Genetics of glucosephosphate isomerase in Aedes togoi (Diptera: Culicidae).

The genetics of glucosephosphate isomerase (E.C. 5.3.1.9) in two strains (Malaysian and Taiwan) of Aedes togoi is reported. Three electrophoretic phenotypes were presented in both sexes. The zymogram patterns were identical in both strains of A. togoi. The phenotypes were governed by a pair of codominant alleles. The allele frequency of the slow-moving band was 0.63 in the Malaysian strain adn was 0,86 and 0.82 in F161 and F169 generations, respectively, of the Taiwan strain. The sample studied was in good accord with Hardy-Weinberg expectation.

Aedes↗
PubMed1980

Pulmonary hemorrhage and immune-complex deposition in the lung. Complications in a patient with systemic lupus erythematosus.

A patient with systemic lupus erythematosus (LE) was admitted with an acute illness characterized by dyspnea, hemoptysis, fever, and diffuse infiltrates revealed by chest roentgenograms. An open-lung biopsy specimen showed massive intrapulmonary hemorrhage, and immunofluorescence and electron microscopic examinations showed granular deposits of IgG within the alveolar walls and pulmonary vessels. Rare, widely scattered foci of infiltration of vessel and alveolar walls by polymorphonuclear leukocytes were also observed. The patient was treated with large doses of prednisone and her condition improved, but she had a second episode of massive hemorrhage eight days after discharge despite maintenance of the prednisone therapy. Her condition again improved over several days, and she has had no pulmonary symptoms for nine months. In some instances, pulmonary hemorrhage in patients with systemic LE may be mediated by polymorphonuclear leukocytes attracted by immune-complex deposits.

Adult↗
PubMed1979

Protein variation and systematics of three subgenera of Malayan rats (Rodentia: Muridae, genus Rattus Fischer).

1. Nine erythrocyte proteins coded by a separate locus each were analysed in and among seven Malayan species of Rattus belonging to three subgenera. 2. Electrophoretic data obtained confirm the specific status of the seven taxa and divide the seven species into three groups which correspond with Ellerman's (1949) subgenera Stenomys, Maxomys and Leopoldamys. 3. A comparative study together with 11 other species of Malayan Rattus previously analysed show that, with few exceptions, the overall relationships among the 18 species based on electrophoretic data correspond well with conclusions based on morphological evidence. 4. Malayan species of Rattus are relatively very diverse genetically (S = 0.27, range 0.01-0.94).

Acid Phosphatase↗
PubMed1978

Protein variation and systematics in Malayan rats of the subgenus Lenothrix (Rodentia: Muridae, genus Rattus Fischer).

1. Electrophoretic variations of 9 erythrocyte proteins, coded by a separate gene locus each, were analysed in and among the 5 Malayan species of Rattus belonging to the subgenus Lenothrix. 2. The average proportion of loci heterozygous per individual for the taxa analysed is 0.037. 3. The results obtained confirm the specific status of the 5 taxa studied. With respect to the relative affinities among the species studied, the present results could resolve the discrepancies between conclusions based on morphological evidence and those based on cytological evidence. 4. The 5 species of Rattus studied may be assigned to 4 groups and comparative data suggest that these groups are relatively distantly related to one another.

Animals↗