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Biomedical subjects

R K Chen

Publications and source records attributed to R K Chen.

11 recordsLinked to original sources
PubMed2006

Assessment of hemodynamics properties of a new-type artificial heart valve prosthesis using catheterization and echocardiography.

OBJECTIVE: The objectives of this study were to assess the hemodynamic properties of the newly developed artificial heart valve prosthesis experimentally in laboratory simulation, in an animal model, and clinically in a human model and to compare the results measured by catheterization and echocardiography. METHODS: (1) Laboratory simulation. The prosthesis was tested using a pulsatile flow simulator in the aortic position. Hydrodynamics parameters were automatically analyzed through a custom-designed data processing program. (2) Animal experiment. Six sheep subjected to mitral replacement with 21-mm-valve prosthesis were measured by open cardiac catheterization intraoperatively. Doppler echocardiography and open cardiac catheterization under dobutamine stress were performed in two sheep subjected to implantation 2.5 years ago. (3) Clinical patient observation. Observations were carried out on 14 patients with aortas replacement and 10 patients with bicuspid replacement using both doppler echocardiography and open cardiac catheterization. RESULTS: (1) Laboratory simulation. The results showed that the value of the transvalvular gradient (DeltaP) decreased with the increase of heart rate, and the values were not greater that 10 mm Hg at any given tissue annulus diameter. (2) Animal experiment. The mean DeltaP value of the six sheep was 5.2 +/- 1.7 mm Hg intraoperatively, while the corresponding DeltaP value of the two sheep 2.5 years after implantation was 6.1 +/- 0.3 mm Hg measured by open cardiac catheterization. (3) Clinical patient observation. The mean DeltaP values in the aortic position measured by catheterization and echocardiography were 6.26 approximately 4.10 and 9.42 approximately 7.48 mm Hg, respectively. The gradients in the mitral position were 2.10 approximately 1.9 and 5.28 approximately 4.10 mm Hg, respectively. CONCLUSIONS: The results demonstrate that the new-type bileaflet heart valve prosthesis only generates a relatively low transvalvar gradient and thus has good hemodynamic properties.

Adult↗
PubMed2005

Giant solitary fibrous tumor of the pleura.

A 42-year-old woman developed an exceedingly big, solitary fibrous tumor of the pleura (SFTP) that occupied the whole right thorax. She complained of worsening dyspnea as her right lung was completely compressed and the mediastinum was pushed to the left side. A successful resection was performed; after reassembly, the tumor measured 20 cm x 22 cm x 30 cm and weighed 5.2 kg. The squashed right lung reached 60 % re-expansion postoperatively and the patient is in good health at 38 months' follow-up.

Adult↗
PubMed2001

[Genetic engineering sugarcane: potential, current status and prospects].

The literatures on potential of genetic engineering in sugarcane, transformation method and its efficiency, effects of promoter and selectable marker on gene expression and on identification of transformant, and achievement of genetic engineering in sugarcane were reviewed. Directions of further research were also suggested.

Carbohydrates↗
PubMed2001

Effects of methylprednisolone and aprotinin on phospholipase D activity of leukocytes in systemic inflammatory response induced by cardiopulmonary bypass.

AIM: To investigate the role of leukocyte phospholipase D (PLD) in systemic inflammatory response induced by cardiopulmonary bypass (CPB) and the effects of methylprednisolone and aprotinin on leukocyte PLD activity. METHODS: Forty-two patients who received CPB open heart surgery were divided into 3 groups: methylprednisolone group, aprotinin group, and control group. Arterial blood (10 mL) was collected for assay of leukocyte PLD activity, myeloperoxidase (MPO) activity, and CD11b expression at 8 different time points in perioperative period. Plasma IL-6, IL-8, and C-reactive protein levels were also determined. RESULTS: At the time point of ascending aorta declamped, leukocyte PLD activity for control group was (18 +/- 8) nmol choline . h-1 . mg-1, which was higher than that of pre-CPB (P < 0.01); the PLD activity for methylprednisolone group was (10 +/- 6) nmol choline . h-1 . mg-1 that was lower than control (P < 0.05), while it had no statistical difference compared with that of pre-CPB. In methylprednisolone group, PLD activity elevation was postponed to the time point of CPB stopped. There was no statistical difference in PLD activity between aprotinin group and control (P > 0.05). After administration of methylprednisolone or aprotinin, leukocyte CD11b expression, plasma IL-6, IL-8, C-reactive protein levels, and MPO activity decreased by different extent. CONCLUSION: Leukocyte PLD activity was elevated significantly in systemic inflammatory response induced by CPB and methylprednisolone partially blunted the CPB-induced inflammatory response by inhibiting PLD activity.

Adolescent↗
PubMed1999

Open-heart surgery in 48 patients via a small right anterolateral thoracotomy.

To limit the trauma to the chest and to achieve a pleasing cosmetic result, we used 2 types of right anterolateral thoracotomy in 48 patients who required open-heart surgery: 1 was a curved incision along the lower edge of the right breast in women with developed breasts; the other was a slanted incision for men and children. These surgical procedures took place between July 1996 and November 1997. Intraoperatively, a right atriotomy was used to repair 11 atrial septal defects and 11 ventricular septal defects, 2 combined atrial and ventricular septal defects, 1 case of a single atrium, and 1 partial atrioventricular canal. A right ventricular outflow tract incision was used to repair 7 ventricular septal defects and 7 ruptured aortic sinus aneurysm. A combination of a right atriotomy and right ventricular outflow tract incision was used for 2 repairs of combined atrial and ventricular septal defects, 3 radical corrections of tetralogy of Fallot, and 2 radical corrections of trilogy of Fallot. A combined right and interatrial septal incision was used for 6 mitral valve replacements and 1 mitral valvuloplasty. Smooth bypass cannulation and satisfactory intracardiac exposure were achieved with the right anterolateral thoracotomy. There was no complication or mortality directly related to the incision. We believe that the right anterolateral thoracotomy is safer and more effective than the median sternotomy for many common congenital and acquired heart diseases. The thoracotomy causes less trauma and results in a cosmetic appearance that is more acceptable to the patient.

Adolescent↗
PubMed1998

Simultaneous determination of benzene, toluene, ethylbenzene, and xylenes in urine by thermal desorption-gas chromatography.

The determination of metabolites of benzene, toluene, ethylbenzene, and xylenes in urine has been used to assess human exposure to these compounds. The analyses of urine samples for these metabolites are tedious and time consuming. The determination of unmetabolized individual compounds in urine has been studied previously with some success. A simultaneous determination of several unmetabolized VOC compounds in urine by thermal desorption-gas chromatography was conducted to assess the exposure of smokers and nonsmokers to these compounds. The method of thermal desorption-GC was sensitive enough to detect a significant difference in exposure levels due to the contribution of light smoking in the environmentally-exposed group.

Adult↗
PubMed1994

[Valvuloplasty of rheumatic tricuspid valve disease].

This paper reports 49 cases with rheumatic tricuspid lesions underwent tricuspid valvuloplasty. Tricuspid stenosis was in 26, and combined with incompetence in 23. Posterior-septal, anterior-septal, and anterior-posterior commissural fusions were 9, 7, and 5 cases respectively. Tricuspid repair was used in all cases, fused chordae, papillary muscles and valvular commissures were each divided, then De Vaga's or Kay's annuloplasty was performed to correct the residual regurgitation. The associated procedures included DVR in 33, MVR in 15, and AVR in 1. Hospital death was 3 cases. All early survivors were followed up (2 months to 7 yrs, mean 4.2 yrs). There was no late death, heart functional class I was in 34, class II in 10 and class III in 2. Echocardiography performed 6 months postoperatively, showed no tricuspid regurgitation was in 38, moderate regurgitation in 8, and the right atrial volume decreased in various degrees. The principles and the methods of tricuspid valve repair in patients with rheumatic tricuspid lesions were discussed.

Adult↗
PubMed1989

[Anticoagulant management of patients with cardiac valve prostheses].

This article reports the methods and results of anticoagulant management in 653 patients with China-made Björk-Shiley mode Tilting Disc Cardiac Valve Prostheses. The total incidence of thromboembolic complications and valve thrombosis is 0.98 per 100 patient-years during the anticoagulation. The incidence of anticoagulant-related hemorrhage is 1.86 per 100 patient-years. In the anticoagulant period, 61 surgical operations were performed on 58 patients. The results showed that anticoagulant can be maintained in minor, superficial operations where blood ooze can be arrested by compression, temporarily discontinued in elective operations, and reversed abruptly by injecting Vitamin K1 in urgent operations. In addition we handled the contradictions between anticoagulant therapy and menses, contraceptive, pregnancy or delivery (29 patients) for 303 female patients favorably. We conclude that our methods gave excellent results, and were reasonable and practicable.

Adolescent↗