Uptake of nickel from industrial wastewater by genetically engineered Escherichia coli JM109 / 生物工程学报

Heavy metal wastewater poses a serious threat to the environment. In comparison to the existing methods of chemical precipitation, ion exchange and carbon adsorption, biosorption is an attractive alternative for the recovery of heavy metals from industrial effluents. However, nickel ion, different from other heavy metal ions, is a more recalcitrant pollutant and has low affinity to many metal tolerant microorganisms. In this study, Escherichia coli JM109 was genetically engineered to simultaneously express a Ni2+ transport system (the product of nixA gene) andoverexpress metallothionein (MT). NixA protein has a high affinity for Ni2+, and metallothioneins (MTs) are capable of binding a variety of heavy metals including Ni2+ . The Ni2+ bioaccumulation performance of the genetically engineered E. coli JM109 was evaluated. Time-course test showed that the bioaccumulation rate was rapid, and 95% of the accumulation was achieved within the first 10 minutes. The maximum Ni2+ bioaccumulation by genetically engineered E. coli cells was dramatically increased from 1.54 mg/g to 10.11mg/g, a more than five-fold increase than that of the original E. coli strain. The isotherm was of Langmuir type. Within the tested pH range (pH 4-10), the engineered cells displayed more resistance to pH variation, retaining up to 80% of the Ni2+ binding capacity at pH 4, while the original E. coli host cells lost 80% of Ni2+ binding capacity at pH 4. The presence of Na+ and Ca2+ affected Ni2+ bioaccumulation, but the effects were not serious, as 71% and 66% of the Ni2+ binding capacities were retained respectively at the concentrations of 1000 mg/L Na+ and 1000 mg/L Ca2+ . However, Mg2+ exerted a severe adverse effect on Ni2+ bioaccumulation, 83% of Ni2+ accumulating capacity was lost when Mg2+ concentration reached 200 mg/L. The effects of different kinds of heavy metals on Ni2+ accumulating were different. The genetically engineered E. coli cell lost less than 45% of its Ni2+ bioaccumulation activity in the presence of 50 mg/L lead or cadmium, 66% in the presence of 25mg/L mercury and 84% in the presence of 40 mg/L copper. The presence of glucose did not improve Ni2+ uptake. Our study suggests that the genetically engineered E. coli JM109 has potential application for effective and efficient recovery of nickel from aqueous solutions.

Congenital coronary artery fistulae in adults: diagnosis and surgical treatment / 中华外科杂志

<p><b>OBJECTIVE</b>To summarize the clinical characteristics, diagnosis and surgical in-treatment results of congenital coronary artery fistulas (CAF) in adults.</p><p><b>METHODS</b>Fourteen patients (8 men, 6 women), aged from 18 to 60 years with a mean of 32 +/- 13 years, underwent surgical correction of CAF between March 1985 and April 2002. Eleven of the 14 patients (78.57%) were symptomatic. The diagnosis of CAF was made by echocardiography or angiocardiography preoperatively. The fistulae originated from the right, left and double coronary arteries in 10 (71%), 3 (21%) and 1 (7%) patient(s), respectively. The fistulae drained into the right ventricle (8 patients), left ventricle (4), right atrium (1) and pulmonary artery (1), respectively. The diameter of fistulae ranged from 0.30 to 1.80 cm with a mean of (1.16 +/- 0.49) cm. There were 6 CAF patients associated with coronary artery aneurysms and 4 CAF patients with other coexisting cardiac defects. The distal fistulae were closed in 10 patients with cardiopulmonary bypass (CPB) and 4 patients without CPB. The coexisting defects were corrected simultaneously.</p><p><b>RESULTS</b>There was no early and late death. One patient had low cardiac output syndrome and cured during early postoperative period. Twelve patients (85.71%) were followed up for a mean period of 3.35 +/- 4.28 years without myocardial ischemia or infarction and recurrent fistulae. Heart function was improved to NYHA functional class I in 11 patients and class II in 1 patient.</p><p><b>CONCLUSIONS</b>All adult patients with CAF who have demonstrable hemodynamic and cardiovascular morphological changes should be surgically treated as early as possible. The appropriate surgical management and reliable myocardial protection are key points of good surgical results.</p>

Long-term results of mitral-aortic valve replacement in 1,154 patients with rheumatic valvular disease / 中华外科杂志

<p><b>OBJECTIVE</b>To analyze the early and long-term results after mitral-aortic valve replacement for rheumatic valvular disease and the determinant factors involved and subsequent therapies.</p><p><b>METHODS</b>1 154 patients receiving combined mitral-aortic valve replacement for rheumatic valvular disease from May 1981 to May 2001 were reviewed. The mean age of the patients was 41.48 +/- 10.00 years. Concomitant valve plasty was performed for associated tricuspid organic or significant functional lesions. Lateral tilting disc or bileaflet valve prostheses were used for replacement. New York Heart Association functional status showed Class III or IV in 91.77% of the patients. Moderate to severe pulmonary hypertension occurred in 29.38% of the patients. The duration of follow-up varied from 8 months to 20 years.</p><p><b>RESULTS</b>The hospital mortality was decreased from 6.50% to 4.45%. The 5-, 10- and l5-year survival rates were 89.46% +/- 1.35%, 86.50% +/- l.91% and 67.86% +/- 6.16%, respectively. The 5-, 10- and l5-year thromboembolic event free rates were 97.80% +/- 0.74%, 88.31% +/- 2.20% and 94.08% +/- 2.29%, respectively. the 5-, 10- and l5-year anticoagulant related bleeding free rates were 94.80% +/- 1.09%, 89.32% +/- 2.10% and 83.12% +/- 3.57% respectively. Cardiac functional status returned to Class II in 98% patients and to Class III in 2% during follow-up.</p><p><b>CONCLUSIONS</b>Both left and right ventricular functions may be impaired as a result of rheumatic valvular disease. Tricuspid valve should be explored during surgery and any significant tricuspid annular enlargement and regurgitation showed be corrected in concomitance. Long-acting penicillin regimen is needed for 3 - 5 years for the prevention of rheumatic fever relapse. A low intensity anticoagulant regimen after valve replacement with prothrombin time targeting at 1.5 - 2.0 times is advisable in lessening anticoagulant related bleeding yet optimizing sufficient prevention against thromboembolic complications.</p>