A novel method for DNA delivery into bacteria using cationic copolymers.

Amphiphilic copolymers have a wide variety of medical and biotechnological applications, including DNA transfection in eukaryotic cells. Still, no polymer-primed transfection of prokaryotic cells has been described. The reversible addition-fragmentation chain transfer (RAFT) polymer synthesis technique and the reversible deactivation radical polymerization variants allow the design of polymers with well-controlled molar mass, morphology, and hydrophilicity/hydrophobicity ratios. RAFT was used to synthesize two amphiphilic copolymers containing different ratios of the amphiphilic poly[2-(dimethyl-amino) ethyl methacrylate] and the hydrophobic poly [methyl methacrylate]. These copolymers bound to pUC-19 DNA and successfully transfected non-competent Escherichia coli DH5α, with transformation efficiency in the range of 103 colony-forming units per µg of plasmid DNA. These results demonstrate prokaryote transformation using polymers with controlled amphiphilic/hydrophobic ratios.

A novel method for DNA delivery into bacteria using cationic copolymers

Amphiphilic copolymers have a wide variety of medical and biotechnological applications, including DNA transfection in eukaryotic cells. Still, no polymer-primed transfection of prokaryotic cells has been described. The reversible addition-fragmentation chain transfer (RAFT) polymer synthesis technique and the reversible deactivation radical polymerization variants allow the design of polymers with well-controlled molar mass, morphology, and hydrophilicity/hydrophobicity ratios. RAFT was used to synthesize two amphiphilic copolymers containing different ratios of the amphiphilic poly[2-(dimethyl-amino) ethyl methacrylate] and the hydrophobic poly [methyl methacrylate]. These copolymers bound to pUC-19 DNA and successfully transfected non-competent Escherichia coli DH5α, with transformation efficiency in the range of 103 colony-forming units per µg of plasmid DNA. These results demonstrate prokaryote transformation using polymers with controlled amphiphilic/hydrophobic ratios.

A stability test of liposome preparations using steady-state fluorescent measurements.

The stability of liposome preparations under the action of the nonionic detergent Triton X-100 was measured using the fluorescent molecular probe octadecylrhodamine B (R18). The probe inserted in the lipid bilayer shows a self-quenched fluorescence and the degree of quenching depends both on the probe concentration and the phase state of the lipid membrane. The addition of detergent to the liposomes produces a steep decrease in self-quenching caused by dilution of the probe in the bilayer. The curves of steady-state fluorescence intensity show an abrupt change in slope that corresponds to the point at which liposomes break down into lipid-detergent mixed entities that are different from the earlier liposome-monodisperse population. The lytic process was followed in parallel by dynamic light scattering (DLS), and the analysis of the DLS results agree with the interpretation of the fluorescence measurements. The probe R18 therefore is a useful marker to test the stability of liposome preparations. The advantages of the present method are discussed by comparison with other techniques.

[Thromboembolic risk factors in atrial flutter. Transesophageal echocardiographic study]. / Factores de riesgo tromboembólico en el flutter auricular. Estudio con ecocardiografía transesofágica.

BACKGROUND: The thromboembolic risk of atrial flutter (AFL) is not well defined. On the other hand, in atrial fibrillation (AF), the echocardiographic demonstration of thrombus or spontaneous echo contrast in the left atria or its appendage, a lower flow velocity in the left atrial appendage, and its reduced mobility, are well known risk factors of thromboembolism. AIM: To study the incidence of these echocardiographic risk factors in patients with AFL. MATERIAL AND METHODS: We prospectively studied 50 consecutive patients with AFL comparing them with two groups of patients with a well known increased risk of thromboembolism: 54 patients with AF and 24 patients with sinus rhythm and severe mitral stenosis (RSEMS). The group of patients with AFL was also compared with a control group of 27 patients with sinus rhythm and no increased risk of thromboembolism. In each group, we studied the presence of thrombi and spontaneous echo contrast in the left atria and left atrial appendage, emptying velocity (Vel A), filling flow (Vel B) and motility of the left atrial appendage and left atrial dimensions. RESULTS: When compared with control patients, AFL subjects had a higher incidence of spontaneous echo contrast in the left atria and left atrial appendage (11 and 42% respectively, p < 0.05); slower flow velocity in the left atrial appendage (Vel A 69.25 +/- 25 and 41 +/- 19 cm/s respectively, Vel B 55 +/- 16 and 46 +/- 20 cm/s respectively, p < 0.05); lower atrial appendage wall motility (4 and 84% respectively, p < 0.001) and a larger left atrium (40 +/- 10 and 45 +/- 0.6 mm respectively, p < 0.05). Patients with AFL had a lower incidence of echocardiographic abnormalities than subjects with AF or RSEMS. Thrombi were found in 2 patients with AFL, 12 patients with AF, 4 patients with RSEMS and in no control patient. CONCLUSIONS: In AFL, there are echocardiographic markers of increased thromboembolic risk in comparison with a control group. Nevertheless, the incidence of these factors is lower than in patients with AF or with RSEMS.

Heart rate variability in severe aortic stenosis.

BACKGROUND AND AIM OF THE STUDY: Autonomic dysfunction may be a risk factor for the generation of arrhythmias and sudden death in patients with severe aortic stenosis; thus, patients with this condition were studied to assess cardiac autonomic function. METHODS: Twelve patients (five males, seven females; mean age 63 +/- 13 years) with severe symptomatic aortic stenosis before and after aortic valve replacement, were compared with a control group matched by age and sex. In the study group, mean fractional shortening was 36.5 +/- 5% and maximal aortic gradient 94.7 +/- 12 mmHg, assessed echocardiographically. Autonomic dysfunction was evaluated by following heart rate variability in both time and frequency domains. Spectral analysis was assessed at very low frequency (VLF: 0.017-0.05 Hz), low frequency (LF: 0.05-0.15 Hz) and high frequency (HF: 0.15-0.50 Hz). Heart rate variability was analyzed during three intervals, between 6:00-8:00 am (morning), 14:00-16:00 (afternoon) and 02:00-04:00 (night), and re-evaluated at 8-10 months after aortic valve replacement. RESULTS: Compared with controls, patients with aortic stenosis presented a significantly lower heart rate variability in the morning and afternoon, analyzed either by time or frequency domain: 50 +/- 22 versus 132 +/- 52 ms (p < 0.05); VLF 5.0 +/- 1.5 versus 7.9 +/- 1.4 ln (ms)2 (p < 0.05); LF 4.9 +/- 1.7 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05); HF 5.3 +/- 1.4 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05). Results at night showed a similar tendency, but were not statistically significantly different. At 8-10 months after aortic valve replacement, heart rate variability was increased significantly during the morning, from 50 +/- 22 to 79.5 +/- 22 ms (p < 0.05); VLF from 5.0 +/- 1.5 to 6.7 +/- 0.8 ln (ms)2 (p < 0.05); LF from 4.9 +/- 1.7 to 6.2 +/- 1.3 ln (ms)2 (p < 0.05). HF values tended to increase, though not significantly so. During the remainder of the day there was also a non-statistically significant increment in all values of heart rate variability. CONCLUSIONS: The study results suggest that patients with severe symptomatic aortic stenosis present with autonomic dysfunction that tends to normalize within the first year of valve replacement.

[Coronary angioplasty and stent placement through the radial artery. Report of a case]. / Angioplastia coronaria e implante de stent a través de la arteria radial. Caso clínico.

Coronary angiography and percutaneous treatment of stenotic lesions have expanded in the last few years, due to availability of better diagnostic equipment. The femoral technique applied to this aims has prevailed, considering its efficacy, safety and wide acceptance. Since the beginning of this decade, an alternative access has been developed, in relation to miniaturization of the required elements to perform coronary diagnostic and therapeutic procedures. This new radial artery access is supported by multiple reports from many centers around the world that are increasingly using the technique. With this access it is possible to perform all the regular procedures done regularly through the femoral route. This case report illustrates a coronary angiography study through the radial access, followed by a stent implantation, through the same route.

[Unstable angina: invasive or conservative management?]. / Angina inestable: manejo invasivo o conservador?

Acute coronary syndromes without ST segment elevation (Non-Q-Infarction and unstable angina) share a common pathophysiology, have no indication of thrombolysis, and should not routinely be catheterized on an emergency basis on admission. They should be put in bed rest, given anti-ischemic medications, aspirin and heparin. The small group of patients that do not stabilize with this medical regimen, should be catheterized, in order to have revascularization if they have the appropriate anatomy. There is nowadays a great controversy in the best management strategy for the larger group of patients that becomes stable after medical treatment installation. The invasive strategy proposes early, routine coronary angiography, and revascularization when anatomy is appropriate. The conservative strategy proposes continued medical treatment with invasive management only indicated by development of spontaneous or inducible ischemia. These two alternative strategies have been tested recently in large, prospective, randomized clinical trials: there is not a definitive answer, but the provisional guideline is that both are reasonably safe and effective.

Effect of urea on biomimetic aggregates.

The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers) was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic), monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied), which leads to an increase in the area per headgroup and also in the loss of counterion affinities.

Effect of urea on biomimetic aggregates

The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers) was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic), monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied), which leads to an increase in the area per headgroup and also in the loss of counterion affinities.

[Variability of the heart rate: its physiopathological basis and its use as prognostic index after acute myocardial infarction]. / Variabilidad de la frecuencia cardíaca: sus fundamentos fisiopatológicos y su utilidad como índice pronóstico post-infarto agudo del miocardio.

The analysis of heart rate variability studies the normal oscillatory changes of the cardiac cycle. These changes are periodical or incidental and are controlled by humoral, sympathetic and parasympathetic stimuli. Frequency domain and time domain are the methods most used to assess heart rate variability. Time domain analyses variations of cardiac cycle using the standard deviation of RR intervals in 24 hours (SDRR) and the percentage of difference between adjacent normal RR intervals of more than 50 ms (pNN50). Frequency domain, converts beat to beat fluctuation of heart rate into different components of frequency by a fast Fourier transformation. They are classified, according to their magnitude, in high frequency (> 0.15 Hz), low frequency (0.04-0.15 Hz), very low frequency (0.003-0.04 Hz) and extremely low frequency (< 0.003 Hz). The high frequency fluctuations are predominantly related to parasympathetic activity whereas the low frequency fluctuations are related to sympathetic and parasympathetic activity. The physiology of very low and extremely low frequency fluctuations remains unclear. Many reports have shown that a decrease in heart rate variability after myocardial infarction may independently identify patients at risk for sudden death. However, the physiopathologic basis of these findings is not yet elucidated.

[Primary coronary angioplasty as a choice treatment in the 1st 6 hours following acute myocardial infarction]. / Angioplastía coronaria primaria como tratamiento de elección en las primeras 6 horas del infarto de miocardio.

Primary coronary angioplasty as treatment of acute myocardial infarction preserves more myocardium and has a lower mortality than thrombolysis. Aiming to assess the feasibility of its use in Chile, we studied 64 patients aged 59 +/- 2 years old, 27 with an anterior wall and 37 with an infero-lateral wall acute myocardial infarction of 118 +/- 62 min of evolution. Coronary angiography, performed 98 +/- 47 min after diagnosis, showed non significant disease in one, one vessel disease in 26 (40%), two vessel disease in 17 (27%) and three vessel disease in 20 (31%) patients. Responsible arteries for infarction were the anterior descending in 26 (40%), circumflex in 9 (14%), right in 27 (42%), a saphenous bridge in one and left main disease in one patient. In one patient with an obstruction over 50% and in two patients with left main disease, angioplasty was not attempted. The procedure was successful (defined as a residual lesion of less than 50%) in 56 of 61 patients (92%) and failed in four. One patient was re-perfused with intracoronary streptokinase. The delay in reperfusion was lower during working than non-working hours (89 +/- 48 vs 113 +/- 39 min). Four patients (6%) died during hospitalization, two had a reinfarction, two had a new vessel occlusion and three had a spontaneous ischemia. Eleven patients were operated during hospitalization and in two this was an emergency procedure. After 1993, mortality was lower (one of 55 patients) than before (three of nine). It is concluded that early coronary angioplasty in acute myocardial infarction is feasible in Chile, with a high degree of success.

[Adult pulmonary stenosis: percutaneous balloon valvuloplasty]. / Estenosis pulmonar del adulto: valvuloplastia percutánea con balón.

The results of balloon valvuloplasty as treatment for pulmonary stenosis in 8 adults (6 male) whose ages ranged from 17 to 58 years are presented. Three patients had been subjected to cardiac surgery 32, 40 and 10 years before. The procedure was performed through the right femoral vein using one or two balloons with a diameter of not less than 20 mm, without complications and excellent tolerance. The pulmonary gradient and the right ventricular pressure were reduced in 7 patients from 81.4 +/- 26.9 to 26.6 +/- 11.3 and from 99.3 +/- 25.5 to 47.7 +/- 13.6 mm Hg respectively (p < 0.0005). During follow up, 6 of the patients have remained in functional capacity I and in two, Doppler ultrasound examination showed a further reduction in valvular gradient. These results are in accordance with other reports and confirm that this technique is the treatment of choice for adult pulmonary stenosis.

[Percutaneous mitral valvuloplasty in 2 pregnant women]. / Valvuloplastia mitral percutanea en dos mujeres embarazadas.

In women with a significative mitral stenosis that become pregnant, medical treatment has limitations and surgical treatment is associated with maternal and fetal mortality. We report two pregnant women in whom a mitral valvuloplasty was performed in weeks 30 and 32 of pregnancy, using the single balloon Inoue technique. The indication for the procedure was the persistence of functional capacity IV heart failure in spite of hospital bed rest and the use of diuretics and beta-blockers. Basal mitral valvular area was 0.6 and 0.9 cm2 and improved to 1.7 and 1.8 cm2 after the procedure; six months later, the areas were 1.5 and 1.7 respectively. The procedure was well tolerated and was performed with abdominal and pelvic shielding. No complications occurred, which allowed hospital discharge in functional capacity I; they were readmitted for delivery, giving birth to two healthy girls. It is concluded that mitral valvuloplasty in safe and effective in pregnant women with mitral stenosis refractory to usual medical treatment.

[Percutaneous mitral valvuloplasty with the Inoue balloon. Report of a case]. / Valvuloplastia mitral percutánea con balon de Inoue. Comunicación de un caso.

Percutaneous mitral commissurotomy has recently been proposed as an alternative to surgery in mitral stenosis. The clinical and hemodynamic results are equivalent to those of surgical treatment. A new technique proposed by Inoue, using a single rubber balloon, with a low incidence of complications, can be performed in a shorter procedure time than the former double balloon technique. A 36 year-old woman with severe mitral stenosis, NYHA FC III, was treated percutaneously using a single rubber balloon designed by Inoue. Her mitral valve area increased from 0.83 to 1.96 cm2, her mean gradient decreased from 15 to 5.8 mmHg and the cardiac output increased from 4.14 to 5.3 l/min. Total procedure time was 2 h and the radioscopic time was 15 min. The follow-up at the fourth month showed persistence of the mitral valve area (2 cm2 at doppler measurement) and the patient was asymptomatic (NYHA FC I). A description of the technique is presented.

[Percutaneous valvuloplasty: a decade of continuous progress]. / Valvuloplastía percutánea: una década de progreso continuo.

Percutaneous balloon valvuloplasty is an interventional procedure designed to treat valve stenosis. The indications, techniques and results depend on the valve being opened. It is currently the treatment of choice for pulmonary valve stenosis. It is an excellent alternative to surgery for mitral stenosis in patients with mobile valves and little abnormality of the subvalvular apparatus. In aortic stenosis it constitutes a gratifying palliative procedure in older patients at high surgical risk. Longer observation is needed to better appreciate the results and indications of balloon valvuloplasty.

[Incidence of myocarditis in patients with dilated cardiomyopathy]. / Incidencia de miocarditis en pacientes con miocardiopatia dilatada.

We performed right ventricular endomyocardial biopsies in 23 patients with dilated cardiomyopathy aged 45 +/- 14 years. All patients had congestive heart failure of unknown etiology dating up to one year before the procedure (57% less than 3 months). NYHA functional class was II in 5, III in 12 and IV in 6 patients. All patients had evidence of systolic dysfunction and a dilated left ventricle (LV diastolic dimension 68 +/- 11 and systolic dimension 55 +/- 11). Definite evidence of myocarditis, based on findings of inflammatory infiltrate and cellular damage, was found in 6 patients (26%), borderline myocarditis in 9 and abnormalities consistent with dilated cardiomyopathy in 8. The incidence of myocarditis here reported is lower than previously figures based on findings of more than 5 lymphocytes per high power field. In this series, clinical and functional aspects of heart failure did not differ in patients with or without evidence of myocarditis.

[Cardiopulmonary resuscitation]. / Resucitación cardiopulmonar.

Cardiopulmonary resuscitation has been used for over 25 years. Recent developments related to a better understanding of the physiology of external massage and to the effect of drugs such as calcium and bicarbonate during cardiac arrest have improved the results of cardiopulmonary resuscitation.

[Percutaneous aortic valvuloplasty: immediate results in calcified aortic stenosis]. / Valvuloplastía aórtica percut[anea: resultados inmediatos en la estenosis aórtica cálcica.

Symptomatic calcific aortic stenosis in elderly patients has a poor prognosis and a relatively high surgical risk. Percutaneous aortic valvuloplasty is a new therapeutic procedure that may be applied in this group of patients. We report immediate results obtained with this technique in a cooperative study of 3 hospitals. In 16 of 19 patients we were able to locate a balloon catheter across the aortic valve following a femoral artery puncture. Mean age was 72 years and almost all patients were considered high surgical risk. Peak aortic gradient fell from 89 + 33 to 47 + 21 mmHg while valve area rose from 0.43 + 0.14 to 0.66 + 0.27 cm2; cardiac output remained unchanged. In 5 patients, an aortic valve area above 0.7 cm2 was obtained. Four patients needed blood transfusion, one developed pericardial tamponade and other recovered uneventfully from ventricular fibrillation. One patient died hours after the procedure in a low output state probably related to aortic insufficiency. We feel that aortic valvuloplasty is indicated in patients with severe calcific aortic stenosis and high surgical risk. Moderate improvement can be obtained with risks commensurate with the severity of the illness.

[Association of coronary disease and valve diseases: implications for coronariography indication]. / Asociacion de enfermedad coronaria y valvulopatias: implicaciones para la indicacion de coronariografia.

We studied 111 patients with valvular heart disease in order to detect associated coronary artery disease (CAD). Fifty had aortic valve disease, 47 mitral lesions and 14 mitro-aortic disease. Coronary angiography was performed in all subjects above 50 years of age and in 13 younger subjects with angina, atypical chest pain, prior myocardial infarction or unexplained left ventricular disfunction. Eight subjects (7.2%) had significant CAD: 1 with triple, 2 with double and 5 with single vessel disease. CAD was diagnosed in 11.5% of 26 patients with angina, in 6% of 17 patients with atypical chest pain and in 6% of 68 patients without pain. CAD was present in males only above age 55. We conclude that in our population, with low incidence of CAD, the association of this disease and valvular heart disease is unusual. Coronary arteriography would be unnecessary in these patients except in the presence of marked risk factors or other clinical findings suggesting CAD, like angina or prior myocardial infarction.