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Biomedical subjects

J M Mao

Publications and source records attributed to J M Mao.

8 recordsLinked to original sources

Constructing new periodic exact solutions of evolution equations.

For the nonlinear Schrödinger equation, the Korteweg-de Vries equation, and the modified Korteweg-de Vries equation, periodic exact solutions are constructed from their stationary periodic solutions, by means of the Bäcklund transformation. These periodic solutions were not written down explicitly before to our knowledge. Their asymptotic behavior when t-->-infinity is different from that when t-->infinity. Near t=0, the spatial-temporal pattern can change abruptly, and rational solitons can appear randomly in space and time. They correspond to new types of "homoclinic orbits" due to different asymptotic behaviors in time.

Journal Article↗

[The synthesis and pharmacological activities of C-galactosides of furanosequiterpenes].

Four new C-galactosides were obtained by treatment of 1-O-trifluoroacetly-2, 3, 4, 6-tetra-O-benzly-alpha-D-galactopranose with 7-methoxy-6-(3-pentenyl)-3, 5-dimethylbenzofuran, 7-acetoxy-6-(3-pentenyl)-3, 5-dimethylbenzofuran and 1, 2-dihydrocacalohastin in the presence of Lewis acid. Their structures and compositions were elucidated by elemental analysis and spectroscopic methods. The results of the pharmacological test indicated that the sesquiterpenes are calcium antagonist but their C-galactosides are calcium agonist.

Calcium↗

No subacute thrombosis and femoral bleeding complications under full anticoagulation in 150 consecutive patients receiving non-heparin-coated intracoronary Palmaz-Schatz stents.

Intracoronary stenting has been shown to have better immediate and long-term clinical outcomes and less restenosis than standard balloon angioplasty. However, the benefit was achieved at the cost of higher rates of coronary thrombosis, bleeding complications, the need for anticoagulation, and longer hospital stay. For the latter reasons there is a tendency to replace the anticoagulants by antiplatelet agents alone after stenting. However, we prospectively monitored 150 consecutive patients (133 men, 17 women, mean age 58.5 years) from two centers since February 1993. They all had coronary artery disease and underwent percutaneous implantation of non-heparin-coated Palmaz-Schatz coronary stents under a full but lower dose of anticoagulation. The femoral approach was used in all patients except one. In the 150 patients, 200 stents were implanted in 165 target arteries with 172 lesions. Stenting was performed without the guidance of intravascular ultrasonography; high-pressure poststenting inflation was used in only 17.3% of patients with less than optimal angiographic results. Coronary angiography was performed at baseline, immediately after the procedure, and after 6 months (mean 207 +/- 53.6 days SD) of stenting. The mean (+/-SD) coronary minimum luminal diameter increased from 0.52 0.31 mm to 3.13 +/- 0.42 mm immediately after stenting was performed and was 2.12 +/- 0.91 mm at 6 months. There was a 0% subacute thrombosis rate and a 0% femoral bleeding complication rate in the whole series. Only three (2%) major events occurred: one Q-wave myocardial infarction from closure of an angioplasty site distal to the stent on a very long lesion, one cerebrovascular accident, and one noncoronary-related death. The only patient who underwent the brachial approach had hematoma; otherwise no other minor event occurred. The mean hospital stay was 4.5 days in one of the two study centers. The long-term clinical follow-up rate was 97.3%. The mean (+/- SD) clinical follow-up period was 589 +/- 363 days. Clinical symptoms improved; the percentage of patients who had angina according to the Canadian Cardiovascular Society functional class II, III, and IV was 31.3%, 44.7%, and 4%, respectively, before stenting was performed and was reduced to 4.7%, 3.7%, and 0%, respectively at 6-month follow-up after stenting was performed. The 6-month angiographic restudy rate was 90.6%, and the restenosis rate was 18.3%. In contrast to other reported series, these results support the idea that with careful puncture technique and meticulous postoperative wound care, intracoronary stenting can be successfully performed with the patient under full anticoagulation without major risks of bleeding and femoral vascular complications. Furthermore with a full but comparatively lower dose of anticoagulation, subacute thrombotic complications can be reduced to 0% even with non-heparin-coated stents without the use of intravascular ultrasound guidance and without the use of adjunctive high-pressure poststenting inflation in most patients. The restenosis rate and long-term clinical outcomes remained very favorable.

Acute Disease↗

Effects of pulse excimer laser irradiation on the human left ventricular wall.

This study was to assess the potential application of excimer lasers in the ablation of myocardium in vitro for the treatment of constant ventricular tachycardia or hypertrophic cardiomyopathy. A fresh human heart and EMG model 103 XeCl pulse excimer laser machine were used. The pulse repetition rate varied from 1 to 7 Hz. Irradiation directly on the left endocardial and epicardial walls lasted for 10 seconds and was repeated 3 times, creating 3 craters. The histological changes were examined by light microscope. Results showed very close relations between the depth or volume of vaporized craters and the pulse repetition rate on the endocardial (r = 0.9674, P less than 0.001 and r = 0.8962, P less than 0.01, respectively) and epicardial walls (r = 0.9602, P less than 0.001 and r = 0.9612, P less than 0.001, respectively). A sharp, clear border without debris or coagulating necrosis was seen under the microscope. We concluded that the pulse excimer laser, differing from Ar+ or Nd:YAG lasers, might be a powerful tool for manipulating the human ventricular wall, but more work needs to be done before it can be widely applied in the treatment of cardiovascular disease.

Chlorides↗

[Percutaneous coronary laser angioplasty in a patient with chronic total obstruction of the right coronary artery].

Percutaneous coronary laser angioplasty was performed in one patient with total occlusion of right coronary artery without further balloon angioplasty in the ablated site. First of all, we used intracoronary urokinase in a total amount of 60,000 units that resulted in opening the total occluded right coronary artery to provide a passage of guidewire of laser catheter. Then a laser catheter was inserted through the guide catheter and its metal cap was in contact with the atherosclerotic lesion. The Nd:YAG laser was activated to vaporize the lesion (total energies of 54 J). Finally, the degree of residual stenosis was reduced from 95% to 20%. Percutaneous coronary laser angioplasty is a new method in treating coronary artery disease, yet it is still in its infant stage and further work is needed to develop this technological procedure.

Adult↗