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Biomedical subjects

M S Chern

Publications and source records attributed to M S Chern.

At least 37 records · Page 2Linked to original sources
PubMed1999

Aberrant infrarenal inferior vena cava as a hindrance to percutaneous transvenous mitral valvuloplasty in a patient with mitral stenosis: case report.

Cardiac catheterization and percutaneous transvenous mitral commissurotomy using the Inoue technique were attempted in a 44-year-old woman with mitral stenosis. The pulmonary arterial wedge pressure was 25 mmHg, mean transmitral diastolic pressure gradient 20.3 mmHg, cardiac index 1.80 L/min/m2, and mitral valve area 0.70 cm2. After the diagnostic catheterization, the guide wire for the transseptal procedure was checked in the middle of the inferior vena cava (IVC). A 7-French end-holed Bermann catheter was then used to detect the course of the IVC. It was found that the IVC coursed along the left border of the 4th and 5th lumbar vertebrae, to the left of the abdominal aorta. At the upper border of the third lumbar vertebra, the IVC returned to the right side of the vertebra. In consideration of the inability to pass the Brockenbrough needle through the detoured infrarenal IVC and the risk of rupturing the vessel, the transseptal procedure and attempted percutaneous transvenous mitral commissurotomy were aborted. Therefore, the patient underwent open mitral commissurotomy instead.

Adult↗
PubMed1998

Late coronary artery stenting in patients with acute myocardial infarction.

BACKGROUND: The safety and efficacy of late coronary artery stenting of the infarct-related artery after acute infarction has not been evaluated previously. METHODS AND RESULTS: Coronary artery stenting was performed in 117 consecutive patients with acute infarction who were receiving ticlopidine/aspirin regimen without coumarin. There were 97 men and 18 women, aged 58+/-11 (mean +/- SD) years. A total of 136 Palmaz-Schatz stents were successfully implanted in 130 lesions 15+/-8 days after acute myocardial infarction (median 9 days) in 115 of 117 (98%) patients. The minimal luminal diameter (MLD) increased from 0.66+/-0.46 to 3.14+/-0.53 mm (P< .001), with an acute gain of 2.49+/-0.61 mm. One patient had acute thrombosis requiring further stenting and another patient received emergency bypass surgery. There was no subacute thrombosis or other complications. During a follow-up duration of 14+/-3 months, 2 patients had angina pectoris develop and 1 died suddenly. Sixty-two patients underwent a follow-up coronary angiography 195+/-36 days after stenting. Restenosis was noted in 8 patients (13%); the MLD was 2.19+/-0.73 mm, the late loss was 0.96+/-0.65 mm (P< .001), the loss index was 0.39+/-0.28, and the net gain was 1.56+/-0.79 mm (P< .001). The angiographic left ventricular ejection fraction increased from 47%+/-12% to 55%+/-12% (P< .001). CONCLUSIONS: Late coronary stenting of the infarct-related artery in patients with acute myocardial infarction is a safe and effective late reperfusion therapy and may be beneficial to the patients.

Adult↗
PubMed1998

Model of computerized academic medical clinic.

In the traditional medical graduation course, the student receives a great amount of information while training at the Outpatient Care; the student assumes the physician's role, collecting all the information regarding the patient's clinical history and learns to get along with patients as well. During the attendance process, several factors interfere in the academic teaching, such as limitations of room numbers, amount of patients, difficulties in obtaining medical records, paper illegibility, among other problems. Due to those difficulties, the Model of Computerized Academic Health Clinic, implies in a new learning paradigm in the medical practice, rethinking the traditional process of learning-attendance, where the old model, in which attendance is restricted to a place, is extended in an open atmosphere of shared knowledge, rich of computer resources. The pilot project was implanted in the Pediatrics General Health Clinic of UNIFESP/EPM. It allows that the fifth-year medical students, residents, trainees and tutors use computerized clinics, connected with the academic net of UNIFESP and to the Internet. All the computing and information resources settled at the Outpatient Care improved the organization of its services, increased the medical students' curiosity, improved their participation in learning through interactive programs and clinical attendance.

Academic Medical Centers↗
PubMed1997

Conserved RY-repeats mediate transactivation of seed-specific promoters by the developmental regulator PvALF.

Transcription of genes DLEC2 and PHSbeta is specifically and coordinately regulated during maturation of Phaseolus embryos. Over-expression of the seed- specific factor PvALF in cotyledon cells results in transactivation of either promoter. PvALF is related to the VP1 protein of maize, which transactivates gene expression via G-boxes, Sph elements and AT-rich sequences. We used deletions and base substitutions in the DLEC2 and PHSbeta promoters to demonstrate that several conserved RY-repeats were necessary for PvALF induction of both genes. A comprehensive mutational and transactivation analysis was used to define functionally the sequence of the DLEC2 repeat RY3 asG/CCATGCxxG/C. We also found that an interaction between RY3 and the 3'-flanking tetranucleotide CCAC increased PvALF transactivation. A preferred spacing and phasing requirement for the RY3 and CCAC motifs suggested the possibility of interactions between cellular factors that recognize either element. The high conservation of Sph-RY motifs in seed-specific promoters from monocots and dicots indicates that organ and temporal specification by factors similar to VP1 and PvALF is common among seed plants.

Fabaceae↗
PubMed1997

Comparison of clinical efficacy and adverse effects between extended-release felodipine and atenolol in patients with mild and moderate essential hypertension.

BACKGROUND: Essential hypertension is a risk factor for cardiovascular disease. Atenolol, a cardio-selective beta-blocker, has been shown to be a safe and effective antihypertensive agent. The extended-release form of felodipine (felodipine ER), a vascular-selective dihydropyridine calcium blocker, is extensively used in Caucasians. However, its effectiveness, tolerability and adverse side-effect have not been assessed in Chinese populations. METHODS: Sitting blood pressure (BP), heart rate, body weight, adverse reaction and serum biochemistry were assessed in 70 patients with mild-moderate essential hypertension treated either with felodipine ER (37 patients), or atenolol (33 patients) for 10 weeks. Each patient was prescribed 5 mg of felodipine ER or 50 mg of atenolol once daily and this daily dosage was doubled to twice daily if necessary. RESULTS: Six patients who received felodipine ER and 3 who received atenolol withdrew from the treatment because of intolerable side effects. Within ten weeks, 81.1% of the patients had responded to a total daily dosage of 5-10 mg of felodipine ER and 81.8% to a daily dose of 50-100 mg of atenolol. By the end of treatment, the mean BP in the felodipine ER group had decreased from 176/104 mmHg at baseline to 145/85 mmHg, while the BP in the atenolol group had dropped from 173/103 mmHg to 145/84 mmHg (NS between the two groups). Heart rate declined in the atenolol group but did not change in patients who received felodipine ER. Overall, patients in the felodipine ER group had a higher rate of adverse reaction (70.3% vs. 39.4%; p < 0.001), and 16.2% of the patients in the felodipine ER group experienced symptoms of hypotension. CONCLUSION: Equivalent doses of felodipine ER and atenolol are effective first-line monotherapeutic agents for the treatment of mild-moderate essential hypertension.

Adrenergic beta-Antagonists↗
PubMed1996

QTc prolongation indicates a poor prognosis in patients with organophosphate poisoning.

This study reviewed emergency department electrocardiograms of 223 patients with organophosphate poisoning from January 1982 to June 1994: 97 (43.5%) had QTc prolongation and were placed in group A; 126 patients without QTc prolongation were designated as group B. Compared with group B, group A patients had a higher mortality (19.6% v 4.8%, P < .001) and a higher incidence of respiratory failure (56.7% v 20.6%, P < .001). Serum cholinesterase levels were determined in the 223 patients: 92 (41.3%) were classified as severe poisoning. 32 (14.3%) as moderate, 41 (18.1%) as mild, and 58 (25.7%) as very mild. The severe group had a high incidence of QTc prolongation (P < .001), a high incidence of respiratory failure (P < 0.001), and a higher mortality rate (P < 0.001) than the other groups. Of the QTc prolongation patients, 59.8% (55/92) had a high incidence of respiratory failure (78.2% v 35.1%, P < .0001) and a higher mortality rate (29.1% v 8.1%, P < 0.05) compared with 40.2% (37/92) of the patients without QTc prolongation in the severe group. In conclusion, a complete electrocardiogram at the emergency department is important and of prognostic value.

Adolescent↗
PubMed1996

The developmentally regulated bZIP factor ROM1 modulates transcription from lectin and storage protein genes in bean embryos.

Expression of the MAT genes DLEC2 and PHS beta, coding for phytohemagglutinin L-subunit and beta-phaseolin, respectively, is coordinately induced in bean embryos at the onset of seed maturation and regulated at the level of transcription. Previously, it was reported that expression of DLEC2 and PHS beta genes is positively regulated by the acidic transcription activator PvALF. This article describes the regulator of MAT1 (ROM1), a basic/leucine-zipper protein that binds to hybrid G box/C box motifs found on the DLEC2 and PHS beta seed enhancers. ROM1 repressed DLEC2- and PHS beta-driven expression and antagonized transactivation of either promoter by PvALF, in a dosage-dependent manner. By contrast, a PvALF/ROM1 hybrid protein activated transcription. Both repression by ROM1 and activation by the hybrid protein required the presence of intact G-box/C-box motifs. The abundance of ROM1 mRNA in embryos was highest during the cotyledon stage and decreased rapidly at the beginning of maturation, as phytohemagglutinin and phaseolin mRNAs were induced. The results demonstrate that ROM1 is a DNA-binding site-dependent repressor and point to its possible role as a negative modulator of PvALF-activated transcription of MAT genes.

Amino Acid Sequence↗
PubMed1996

The regulator of MAT2 (ROM2) protein binds to early maturation promoters and represses PvALF-activated transcription.

The regulation of maturation (MAT)- and late embryogenesis (LEA)-specific gene expression in dicots involves factors related to ABI3, a seed-specific component of the abscisic acid signal transduction pathways from Arabidopsis. In French bean (Phaseolus vulgaris), the ABI3-like factor, PvALF, activates transcription from MAT promoters of phytohemagglutinin (DLEC2) and beta-phaseolin (PHS beta) genes. We describe the regulator of MAT2 (ROM2) as a basic leucine zipper (bZIP) DNA binding protein that recognizes motifs with symmetric (ACGT) and asymmetric (ACCT) core elements present in both MAT promoters. ROM2 antagonizes trans-activation of the DLEC2 promoter by PvALF in transient expression assays. Repression was abolished by mutations that prevented binding of ROM2 to the DLEC2 seed enhancer region. Moreover, a hybrid protein composed of a PvALF activation domain and the DNA binding and dimerization domain of ROM2 activated gene expression, indicating that ROM2 recognizes the DLEC2 enhancer in vivo; consequently, ROM2 functions as a DNA binding site-dependent repressor. Supershift analysis of nuclear proteins, using a ROM2-specific antibody, revealed an increase in ROM2 DNA binding activity during seed desiccation. A corresponding increase in ROM2 mRNA coincided with the period when DLEC2 mRNA levels declined in embryos. These results demonstrate developmental regulation of the ROM2 repressor and point to a role for this factor in silencing DLEC2 transcription during late embryogenesis.

Abscisic Acid↗
PubMed1996

Pulmonary pseudosequestration receiving arterial supply from a coronary artery fistula. A case report.

A forty-eight-year-old man with a history of pulmonary tuberculosis and scarring of both hila and upper lobes was noted to have bilateral pulmonary pseudosequestration, in which the blood supply originated from a coronary artery fistulous vessel arising from the left circumflex artery and draining into the pulmonary artery. This is the first reported patient with the source of blood supply to the pulmonary pseudosequestration arising from a coronary artery fistula.

Bronchopulmonary Sequestration↗
PubMed1996

The half-moon sign. A useful roentgen sign of saccular aneurysm of the aortic arch.

OBJECTIVE: The half-moon sign is defined as a shadow seen on the lateral chest radiograph consisting of a smooth, partially demarcated opacity with the rounded portion of the half moon projecting over the aortic lumen at the level of the aortic arch, but the rest of the opacity merging with the aorta. In this study, we intended to evaluate the clinical usefulness of half-moon sign in aiding a diagnosis of saccular aneurysm of the aortic arch. METHODS: This series consisted of 57 patients with aortic arch aneurysm and 46 patients with a variety of nonvascular intrathoracic masses that presented as soft-tissue masses adjacent to the aortic arch on the frontal chest radiographs. The half-moon sign was evaluated independently by two senior chest radiologists who had no knowledge of the final causes. RESULTS: The half-moon sign was shown on the lateral chest radiographs in 5 of 10 patients with saccular aortic arch aneurysm but absent in 47 patients with fusiform aortic arch aneurysm. Furthermore, this roentgen sign was not seen on the lateral chest radiographs in 46 patients with nonvascular intrathoracic masses. In this selected population, the sensitivity and specificity of the half-moon sign in aiding a diagnosis of saccular aneurysm of the aortic arch were 50% and 100%, respectively. CONCLUSION: The half-moon sign shown on the lateral chest radiograph is highly suggestive of the saccular aortic arch aneurysm.

Adult↗
PubMed1996

Apolipoprotein B 3' hypervariable repeat genotype: association with plasma lipid concentration, coronary artery disease, and other restriction fragment polymorphisms.

Apolipoprotein B gene 3' variable number tandem repeat (VNTR) and related regions were amplified by PCR and analyzed by agarose gel electrophoresis. Eighteen VNTR alleles (VNTR25, 26, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 58, 60) and 45 genotypes were observed in 477 Taiwanese subjects. The VNTR35 allele and genotype VNTR35/35 were observed most frequently in this population. The polymorphism information content was 0.62. Some minor alleles, such as VNTR25 and 60, were found only in coronary artery disease (CAD) and stroke patients in our sampling, and no statistically significant difference was observed in VNTR allelic frequency between control and CAD or stroke patients. Significant differences in allelic distribution of some VNTR alleles were observed between our normal Taiwanese population and a Caucasian group studied by others. VNTR43-47 and AluI+ (coding Ala591) restriction fragment length polymorphism (RFLP) as well as VNTR49-60 and EcoRI- (coding Lys4154) RFLP were found to be highly coinherited. No apparent association between the VNTR genotype and plasma lipid concentration was observed; however, for the same genotype, the CAD and stroke patients frequently showed higher lipoprotein(a) and lower HDL cholesterol concentrations than the control group.

Alleles↗
PubMed1996

Mucoid impaction of the trachea simulating a tumor: a case report.

Mucoid impaction of the trachea simulating a tumor has been rarely reported. We report such a case tomographically presenting as a tumor in a 75-year-old woman with chronic obstructive pulmonary disease (COPD). A rapid change in the shape of tracheal shadow with sharp angle was also shown tomographically. It is suggested that a changing shadow in the trachea demonstrated by tomography may be of value in distinguishing mucoid impaction of the trachea from true neoplasm.

Aged↗
PubMed1995

Multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula.

The purpose of this study was to examine the advantages of multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula, specifically in depicting the origin, the course, and the drainage site. Seven consecutive patients ranging in age from 20 to 72 years with a suspected coronary artery fistula underwent conventional transthoracic and multiplane transesophageal echocardiographic studies between March 1993 and July 1994. When a coronary artery fistula was noted, the origin, the course, and the drainage site were carefully searched for. All patients then underwent a cardiac catheterization with the performance of coronary angiography. A large right coronary artery fistula was detected in three patients; one of them had a drainage to the posterior left ventricle, one to the lateral right ventricle, and the other to the medial aspect of the right ventricle just below the insertion of the septal leaflet of the tricuspid valve. A small coronary artery fistula arising from the left coronary artery was noted in four patients, two from the left anterior descending artery and the other two from the left circumflex artery. Three of these four patients had a drainage to the main pulmonary artery and one to the left ventricle. The drainage site was clearly depicted in all seven patients, whereas the origin and the course were precisely defined in five patients by using multiplane transesophageal echocardiographic examination. The multiplane transesophageal echocardiography provides a panoramic view of the coronary artery and the fistulous vessel with a precise definition of the origin, the course, and the drainage site of the fistula. Therefore it is the noninvasive diagnostic mode of choice.

Adult↗
PubMed1995

Pulmonary gangrene: a case report.

Pulmonary gangrene is a rare complication of severe pulmonary infection in which a pulmonary segment or lobe is sloughed. In the English literature, pulmonary gangrene secondary to bacterial infection is uncommon, and fewer to other etiologies. Characteristic roentgen patterns of a mass within a cavity is the hallmark of this disease, which differentiates from a lung abscess. Some authors have emphasized that surgical resection of the infected lobe is the principal option of treatment. In contrast, some have advocated that patients with pulmonary gangrene can be managed with medical therapy. Recently we successfully treated a case of pulmonary gangrene with appropriate antibiotics and percutaneous small bore catheter drainage, even though the complication of bronchopleural fistula was encountered, which led to prolonged hospitalization. The serial roentgenograms and the pictures of computed tomography (CT) will be demonstrated.

Gangrene↗