Heterologous expression of phaC2 gene and poly-3-hydroxyalkanoate production by recombinant Cupriavidus necator strains using canola oil as carbon source.

Many heterologous transformation studies have been carried out using the Cupriavidus necator PHB-4 strain to investigate the expression characteristics of various polyhydroxyalkanoate (PHA) synthase enzymes. In this study, we generated a recombinant C. necator PHB-4 strain by transforming a plasmid (pMRC03) harbouring the synthetic phaC2 gene of Pseudomonas putida CA-3. Under conditions favourable for expression of the phaC2 P.putCA-3 gene, canola oil was used as carbon source for the synthesis of PHAs. The expressed synthase polymerised monomers of 3-hydroxybutyrate (3-HB), 3-hydroxyvalerate (3-HV) and 3-hydroxyhexanoate (3-HHx) in the recombinant C. necator PHB-4 (pMRC03) strain. We then co-expressed the phaC2P.putCA-3 gene with the native phaC1C.ne gene in wild type Cupriavidus necator H16 (C. necator H16 (pMRC03)). This co-expression produced a PHA blend of 3-HB, 3-HV, 3-HHx and 3-hydroxyoctanoate (3-HO) monomers in the presence of canola oil. Gas chromatography analysis revealed the presence of 94mol% 3-HB, 1mol% 3-HV, 4mol% 3-HHx and 1mol% 3-HO in a tetra-polymer. Thus, we confirmed that a synthetic phaC2 gene encoding the synthase enzyme is functionally active with substrates ranging from short to medium chain length PHAs.

Production of polyhydroxyalkanoates (PHAs) with canola oil as carbon source.

Wautersia eutropha was able to synthesize medium chain length polyhydroxyalkanoates (PHAs) when canola oil was used as carbon source. W. eutropha was cultivated using fructose and ammonium sulphate as carbon and nitrogen sources, respectively, for growth and inoculum development. The experiments were done in a laboratory scale bioreactor in three stages. Initially, the biomass was adapted in a batch culture. Secondly, a fed-batch was used to increase the cell dry weight and PHA concentration to 4.36 g L(-1) and 0.36 g L(-1), respectively. Finally, after the addition of canola oil as carbon source a final concentration of 18.27 g L(-1) PHA was obtained after 40 h of fermentation. With canola oil as carbon source, the polymer content of the cell dry matter was 90%. The polymer was purified from dried cells and analyzed by FTIR, NMR and DSC using PHB as reference. The polymer produced by W. eutropha from canola oil had four carbon monomers in the structure of the PHA and identified by 1H and 13C NMR analysis as 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxyoctanoate (3HO), and 3-hydroxydodecanoate (3HDD).

[Balloon valvuloplasty in stenotic bioprosthesis]. / Valvuloplastía con balón en bioprótesis estenóticas.

The results of balloon valvuloplasty performed on five patients with stenotic bioprosthesis treated in the Hospital de Cardiología Centro Médico Nacional Siglo XXI, are presented. All five bioprosthesis were right sided, two in tricuspid position, one in pulmonary valve position and two in valvulated conduits from right ventricle to pulmonary artery. In all cases a pressure gradient reduction was achieved, an improvement of clinical functional class and heart failure manifestations were obtained. Mansfields balloons were used. One in two patients, and two balloons in three. We had not complications with the procedure. We conclude that balloon valvuloplasty on bioprosthesis is a safe and dependable procedure to be used in right sided bioprosthesis.

Percutaneous transluminal ultrasonic angioplasty: preliminary clinical report of ultrasound plaque ablation in totally occluded peripheral arteries.

Peripheral arterial obstructive disease has been treated with ultrasound ablation. Thirty two patients (pts), mean age 67 +/- 10 years underwent angiosonoplasty, with a prototype ultrasonic system, due to severe claudication (31%), rest pain (44%), rest pain and ulceration (25%). Angiosonoplasty was successful in 26/32 (81%) stenoses, (1/2 iliac, 9/2 femorals, 11/12 popliteal, 5/6 tibial). Angiography before and after angiosonoplasty confirmed that the lesions were successfully opened, (81%, p less than 0.05). A mean of 3 +/- 2 passes were required to adequately remove sufficient plaque. Balloon angioplasty was used in combination with angiosonoplasty in 11/32 (34%) occluded vessels. Complications included groin hematoma in 4 pts (12%) and vascular spasm in two patients (6%). Within 24 hours, 27/32 (94%) pts were discharged clinically improved. Reocclusion occurred in 4 pts (12%) immediately after the procedure. Ankle brachial indices significantly increased from 0.52 +/- 0.10 before to 0.70 +/- 0.12 after (p less than 0.05). In conclusion, the use of ultrasound energy to ablate atherosclerotic plaque would appear safe, and has shown no restenosis and a low incidence of complications over a six month period.

[Balloon catheter valvuloplasty for calcified aortic stenosis in adults. Report of a case and review of the literature]. / Valvuloplastía con catéter de balón en la estenosis aórtica calcificada del adulto. Reporte de un caso y revisión de la literatura.

The first procedure of balloon valvuloplasty in adult calcific aortic stenosis was performed in Mexico on July 17 of 1987. It was a 69 year old female with calcific aortic stenosis and unstable, progressive angina pectoris. Cardiac catheterization showed trans-aortic gradient of 90 mmHg, minimal aortic regurgitation and ejection fraction of 85 percent. Aortic valvuloplasty was performed immediately after cardiac catheterization using the arterial retrograde way by means of a 15 mm. in diameter catheter initially and another of 18 mm. in diameter afterwards. At the end of procedure the gradient diminished to 56 mmHg and an slight increase of the aortic insufficiency was observed. The Doppler echocardiogram showed decreased severity of the stenosis. The patient was discharged asymptomatic and continued to do well for six months. She died suddenly after that period of time. A review of the literature is also presented.

[Angina pectoris with normal coronary arteries]. / Angor pectoris con coronarias normales.

Twelve patients 8 females and 4 males, whose ages varied from 33 to 60 years (median 50.6 years), were seen at the Hospital for Cardiology and Neurology of the Mexican Institute for Social Security. All were diagnosed as having angor pectoris, through the clinical history and physical exam. Three patients had stable angor and in nine it was of an unstable type. The resting ECG showed signs of subepicardial ischemia in five cases. In eight the stress ECG according to the Bruce technic showed depression of the ST segment over 1 mm. In one patient atrial stimulation was performed with a pacemaker and ischemic changes of the ST segment were normal in all cases; in two however, coronary spasm that reversed with nitroglycerin appeared. The left ventriculogram was normal in all but one that revealed diaphragmatic hypokinesia associated with right coronary spasm. All patients were followed from two to fifty six months (median 19.4), and only in one case the angor pectoris remained unchanged. In all others it decreased or disappeared. During this time there were no deaths, myocardial infarctions or severe arrhythmias.