Contact-line friction of liquid drops on self-assembled monolayers: chain-length effects.

The static and dynamic wetting properties of self-assembled alkanethiol monolayers of increasing chain length were studied. The molecular-kinetic theory of wetting was used to interpret the dynamic contact angle data and evaluate the contact-line friction on the microscopic scale. Although the surfaces had a similar static wettability, the coefficient of contact-line friction zeta0 increased linearly with alkyl chain length. This result supports the hypothesis of energy dissipation due to a local deformation of the nanometer-thick layer at the contact line.

[Prognosis significance of blood homocysteine after myocardial infarction]. / Significado prognóstico da homocisteinemia após enfarte do miocárdio.

INTRODUCTION AND AIMS: Homocysteinemia is an independent risk factor of coronary artery disease and of myocardial infarction. In the present study we intend to relate fasting homocystein levels to prognosis after a myocardial infarction. METHODS: From 1990 to 1992, we studied fasting homocysteinemia levels on a group of 112 patients aged under 56 years that had suffered a myocardial infarction between 3 and 12 months before. We obtained, the patients names, addresses, phone numbers and physicians' name. Seven years later (on average) we collected data regarding the patients evolution, consulting medical records, their physicians or by personal contact. We evaluated complications, namely mortality, vascular morbidity, such as unstable angina, re-infarction, stroke, and the need for invasive procedures (catheterism, PTCA, CABG). According to previous studies of the group, we used a cut-point of 10.10 mumol/L to define patients with normal or pathological levels of homocysteinemia. We excluded all patients that took vitamin B supplements, co-factors of HC metabolism, during this follow-up. RESULTS: We were able to obtain data on 110 patients. Patients with normal HC levels (n = 62) presented less global complications (26 versus 72%, p < 0.0001), non significant tendency to have lower mortality (1.6 versus 6%), had lower morbidity (14 versus 36%, p < 0.01) and lower invasive procedure need (18 versus 48%, p < 0.001). In the group with pathological homocystein levels (n = 48), those with higher homocystein levels presented a higher degree of complications. CONCLUSIONS: In this population with myocardial infarction under 56 years of age, a high homocysteinemia level is an important prognostic factor. This study suggests that we can improve the prognosis and decrease the complications after myocardial infarction by lowering elevated homocystein levels.

[Cardiac amyloidosis: review of the literature]. / Amiloidose cardíaca: revisão da literatura.

The authors review the clinical impact of cardiac amyloidosis and new aspects concerning the management of this disease in the literature. Cardiac amyloidosis accounts for 5-10% of non-coronary myocardial disorders. It is a distinct form of cardiomyopathy with a severe prognosis. The authors review the role of endomyocardial biopsy and the relative sensitivity of non-invasive diagnostic methods. Chemical and genetic typing of amyloid, which is of considerable clinical value, is also reviewed due to recent evidence of treatment for different types of systemic and cardiac amyloidosis, such as the most common hereditary form caused by transthyretin gene mutation.

[Pharmacological stimulation with dipyridamole in thallium-201 myocardial perfusion scintigraphy: a study of the secondary effects]. / Estimulação farmacológica com dipiridamol na cintigrafia miocárdica de perfusão com tálio-201: estudo dos efeitos secundários.

To evaluate the safety of intravenous dipyridamole thallium-201 imaging as an alternative to exercise thallium imaging in the evaluation of coronary artery disease, clinical data from 140 patients were retrospectively analyzed. Adverse effects were experienced by 39 patients (27.9%) with a total number of 52 effects: chest pain (23), dizziness (13), headache (7), nausea (7), dyspnea (2). All patients presented complete relief of symptoms. In 15 patients administration of aminophylline was necessary. Major effects (fatal and non fatal myocardial infarction and acute bronchospasm) were not registered. Vital sign data change observed after infusion of dipyridamole was: decreased blood pressure and increased pulse rate. Patient's age and incidence of coronary artery disease did not differ significantly in the subgroup of patients with adverse effects versus the group of patients without it.

Homocysteinaemia after methionine overload as a coronary artery disease risk factor: importance of age and homocysteine levels.

BACKGROUND: Homocysteinaemia is now accepted as an independent risk factor for coronary artery disease (CAD). Our goal was to study the influence of age plasma homocysteine level on the CAD risk attributable to homocysteinaemia. METHODS: We studied a group of 98 patients under 55 years of age who had suffered a myocardial infarction 3-12 months before the study. The patients were matched by sex and age with a group of 98 controls without vascular disease. We measured the plasma homocysteine levels 6h after a methionine overload of 0.1 g/kg body weight in patients and controls. Afterwards, the odds ratio for homocysteinaemia was determined by homocysteine level, and that for hyperhomocysteinaemia (homocysteine level > 34 mumol/l) by age group. RESULTS: After methionine loading, the homocysteine odds ratio varied from 0.47 (homocysteine level < 23 mumol/l) to 2.88 (homocysteine level > 34 mumol/l). In patients under the age of 46 the odds ratio for hyperhomocysteinaemia was 18.6. In patients between 46 and 55 years of age the odds ratio for hyperhomocysteinaemia was 1.2. CONCLUSIONS: Low homocysteine levels are protective against CAD, and the higher the homocysteine level the higher the coronary risk appears to be. This clearly means that heterozygosity for cystathionine beta synthase deficiency alone is not enough to explain the vascular risk associated with homocysteinaemia. Hyperhomocysteinemia was shown to be a significant risk factor only in patients under the age of 46 years old.

[Acute juvenile myocardial infarct. A clinical case and review of the literature]. / Enfarte agudo do miocárdio juvenil. Caso clínico e revisão da literatura.

Authors report one case of myocardial infarction in a young man 23 years old. Prevalence of acute myocardial infarction under the age of 35-40 years is not negligible. Pathogenic mechanisms, risk factors, clinical presentation, prognosis, and findings in selective coronary angiography are reviewed.

[Significance of the persistence of ST segment elevation in anterior infarction]. / Significado da persistência da elevação do segmento ST no enfarte anterior.

OBJECTIVE: Persistent ST segmentary elevation in anterior myocardial infarction was classically attributed to ventricular aneurysm. This association is now considered controversial. We studied the association between this electrocardiographic finding and the left ventricular wall motion abnormalities and global function. DESIGN: Retrospective study. SETTING: Patients admitted to Hospital de Pulido Valente Coronary Care Unit in Lisbon with anterior myocardial infarction who were submitted to angiographic study. PATIENTS: 94 patients were included in the study. METHODS: The global ejection fraction, the regional wall motion abnormalities, the coronary artery disease extension, the patency and the proximal involvement of the left anterior descending artery were investigated. RESULTS: 56 of the 94 patients (60%) had persistent ST segment elevation and 38 (40%) had isoelectric ST segment. The ejection fraction was markedly depressed in the group with elevated ST segment (36.2 SD 17.6) in contrast with the group with isoelectric ST segment (49.3 SD 14.8) (p < 0.001). The group with persistent ST segment elevation had more advanced degrees of left ventricular asynergy (42/58-75%) than the group with isoelectric ST segment (12/38-32%) (p = 0.02). The other studied angiographic variables did not differ between the two groups. CONCLUSIONS: The group with persistent ST segment elevation was associated with advanced degrees of left ventricular asynergy and greater left ventricular function depression. The ventricular aneurysm was exclusive of the first group.

[Homocysteinemia as a risk factor for early myocardial infarct--a case-control study]. / A homocisteinemia como factor de risco de enfarte do miocárdio precoce--estudo de casos e controlos.

PURPOSE: To investigate if hyper-homocysteinemia represents an independent risk factor of early coronary disease. METHODS: We studied a group of patients under 45 years old, that suffered a myocardial infarction from 3 months and 1 year before the study. The patients were matched with a group of normal controls of a check-up program, in terms of age, sex, smoking habits, presence of hypertension, obesity, (Quetelet Index), presence of diabetes, basal glycemia, total cholesterol, LDL and HDL cholesterol. Later we measured to patients (Pts) and controls (Cts) the plasmatic basal homocysteinemia (B HC) and 6 hours after a methionine overload of 0.1 g/kg body weight (L HC). RESULTS: [table: see text] CONCLUSIONS: In this study hyper-homocysteinemia appears as an independent risk factor of early coronary disease. The measurement of homocysteinemia after the methionine loading test was more discriminative than the basal measurement.

[What is the value of myocardial perfusion studies with isotopes in patients with complete left bundle branch block?]. / Qual o valor dos estudos de perfusão miocárdica com isótopos em doentes com bloqueio completo de ramo esquerdo?

The prognosis of left bundle branch block is determined by associated cardiovascular disease. Exercise electrocardiography is not helpful in detecting ischemia in these patients. Exercise thallium-201 scintigraphy has been widely accepted for that purpose. The authors made an overview of several studies suggesting that exercise thallium-201 scintigraphy has low specificity regarding left anterior descending coronary artery disease. They also review the mechanisms of perfusion defects in patients with left bundle branch block without coronary artery disease. One important question to be clarified is weather small defects are unrelated to coronary artery disease. Finally the authors analyse a few methods to increase diagnostic accuracy of perfusion scintigraphy in left bundle branch block. First the employment of a new criterium that requires the apex to be abnormal to indicate left anterior descendent artery disease. Second Pharmacological Stress with Dipyridamole or Adenosine. Third imaging with Tc-99m-MIBI.

Comparison of the effects of a controlled-release formulation of isosorbide-5-mononitrate and conventional isosorbide dinitrate on exercise performance in men with stable angina pectoris.

Thirty-three men with stable exercise-induced angina pectoris entered a randomized, double-blind, crossover study in which controlled-release isosorbide-5-mononitrate 60 mg once daily was compared with conventional isosorbide dinitrate 20 mg 3 times daily. Each drug was given for 2 weeks. Twenty-eight patients completed the study and data on exercise variables are available in 23 patients. Treatment with either drug resulted in significant antianginal effects, when measured 6 hours after a single dose and after 2 weeks of therapy compared with baseline placebo; however, there were significantly fewer signs of myocardial ischemia during treatment with isosorbide-5-mononitrate. There was no evidence of tolerance to either drug treatment but a significant attenuation of resting blood pressure (but not of exercise blood pressure) was observed with both drugs. Headache was the only clinically significant adverse event during therapy and it occurred more frequently in the isosorbide dinitrate treatment group (p less than 0.05 vs placebo); 3 such patients had to withdraw from the study because of headache. Thus, once-daily, controlled-release isosorbide-5-mononitrate appears as effective as conventional isosorbide dinitrate 3 times daily in patients with stable angina pectoris. The once-daily administration is convenient and improves patient compliance.

Detection of rejection after heart transplantation. A computerized precordial mapping experience.

A low-cost modular compact personal computer-based system for surface precordial mapping (SPM) developed by the authors was used to detect rejection periods, documented by endomyocardial biopsy (EB), in heart transplant patients on cyclosporine A therapy. Data were collected with a matrix of 35 Ag-AgCl electrodes positioned over the precordio with anatomical references within 12 hours of EB. For each acquisition the authors computed the root mean square waveform from all signals collected to assess the accuracy of the maximum value of the RMS waveform (mRMS) parameter to detect rejection episodes. A mRMS variation of 20% in consecutive mapping acquisitions was the decision criterion. In EB, only presence or absence of acute rejection was considered. Eleven heart transplant patients were studied and 46 acquisitions were done. The mRMS obtained with SPM showed a sensitivity of 69% and a specificity of 91%, with a positive predictive value of 75% and negative value of 88%. The results indicate that surface precordial mapping may be promising for monitoring rejection.