Can microwave radiation at high temperatures reduce the toxicity of fibrous crocidolite asbestos?

Exposure of animals and humans to crocidolite asbestos fibers produces fibrosis and two types of cancers: bronchogenic carcinoma and mesothelioma. It is therefore desirable to reduce toxicity of these fibers without affecting their other characteristics. In this study, commercial crocidolite asbestos fibers were radiated with microwave radiation at different temperatures. Radiated fibers and nonradiated original fibers were then studied by Mössbauer spectroscopy to quantify the amount of ferric and ferrous ions present at structurally different sites in each crocidolite sample. They were also studied for their ability to initiate the peroxidation of linoleic acid to assess the effect of radiation on this process. Results showed that microwave radiation reduced the total Fe2+/Fe3+ ratio. This reduction produced a concomitant decrease in the ability of the radiated samples to peroxidize linoleic acid.

Effect of nitrates on the frequency of left ventricular free wall rupture complicating acute myocardial infarction: a case-controlled study.

Although up to 33% of all deaths from acute myocardial infarction are attributable to left ventricular free wall rupture, data showing a beneficial effect of drugs on this complication are scarce and contradictory. The aim of our study was to investigate the effect of nitrate therapy (intravenous or oral) during the first days after acute myocardial infarction on the frequency of free wall rupture in human beings. In a retrospective case-controlled study, 91 patients with free wall rupture complicating acute myocardial infarction demonstrated on autopsy or operation were compared with 182 control patients with acute myocardial infarction without rupture. The risk of sustaining free wall rupture was approximately 30% lower in patients receiving nitrates: (crude odds ratio 0.62; adjusted odds ratio 0.73 p 0.038). The data analysis demonstrates a possible association between nitrate use and frequency of left ventricular free wall rupture in patients with acute myocardial infarction. Nitrates seem to reduce the risk of rupture by approximately 30%.

Early diagnosis of subacute free wall rupture complicating acute myocardial infarction.

Of 2608 consecutive patients with acute myocardial infarction, 24 developed subacute free wall rupture (= 0.92%; 95% C.I. = 0.6-1.4). Clinical manifestations varied widely (shock on admission; 25% of cases; severe arrhythmias followed by shock: 17%; shock during hospital stay: 42%; symptoms suggestive of infarct extension without shock: 17%). The electrocardiograms were confusing rather than revealing: 56% of patients showed new ST segment elevations of 0.2 to 1 mV in the infarct-related leads, while autopsy or creatinine phosphokinase evidence of infarct extension was missing. In the first 21 cases, therefore, no definitive diagnosis was made before autopsy. Using 197 infarct patients in cardiogenic shock or with infarct extension during the acute stage, i.e. a patient group with comparable clinical manifestations, as control group, a logistic regression model was generated in which the variables age, lateral wall involvement and history of hypertension were used for estimating the probability of subacute rupture. In fact, probability may rise to more than 40% in major subgroups. As death occurred after a median interval of 8 h (45 min-6.5 weeks) following the onset of rupture symptoms, echocardiography must be performed urgently in all cases presenting symptoms of shock or infarct extension. Pretest probability which can be roughly estimated from our model as well as sensitivity and specificity of individual echocardiographic or clinical parameters are indispensable for correct therapeutic decisions. The routine application of this algorithm in our department contributed to a timely diagnosis in the last three consecutive cases of whom one patient survived.

Activation of UICC crocidolite: the effect of conversion of some ferric ions to ferrous ions.

Asbestos fibers catalyze the generation of oxygen-centered radicals in the presence of oxygen or hydrogen peroxide. The amount of iron in asbestos fibers, its oxidation state, and its availability to specific chelating agents determine their ability to catalyze the aforementioned reactions. In the present study, the activation of UICC crocidolite was achieved by converting some of the ferric ions into ferrous ions. The activation process did not interfere with the size distribution, surface area, or crystal structure of these fibers. Although oxygen-centered radicals generated and lipid peroxidation produced by asbestos fibers are reported to play an important role in their toxicity, factors such as size, surface area, and durability are considered to be crucial determinants of fiber toxicity and carcinogenicity. The employment of the activated crocidolite in animal experiments to help further elucidate the importance of oxygen free radicals and lipid peroxidation in fiber-induced diseases is therefore proposed.

[Spatial distribution of the action potentials of the sural nerve]. / Feldverteilung des Aktionspotentials des N. suralis.

We investigated the spatial distribution of the sural nerve sensory nerve action potential (SNAP) in 25 healthy subjects between 21 and 50 years. Stimulation was achieved through surface electrodes at the lateral malleolus. Recordings were made 15-18 cm proximal to the site of the stimulation from different positions on a line perpendicular to the sural nerve using needle electrodes insulated except for the tip. The amplitude of the SNAP decreased on both sides of the potential of highest amplitude. 10 mm lateral to the potential of highest amplitude the mean amplitude was reduced to 55%. The latency of the first positive phase decreased within increasing distance from the largest SNAP. We explained this with different influence of more distal, earlier depolarized nerve segments on the locally generated SNAP. In 20 subjects we performed an additional recording using an uninsulated needle electrode that was placed 3-4 cm subcutaneously perpendicular to the sural nerve. The latency of the SNAP recorded in this way was similar to the latency of the largest SNAP using the insulated needle electrode; however, the amplitude was smaller by 19%. We recommend for clinical practice to use the uninsulated needle in case the SNAP is smaller than 4 microV.

[Presumed "successful" fibrinolysis in unrecognized acute aortic dissection]. / Vermeintlich "erfolgreiche" Fibrinolyse bei nicht-erkannter akuter Aortendissektion.

Thrombolysis (1,500,000 IU streptokinase during 60 minutes and 500 mg acetylsalicylic acid was started in a 43-year-old woman with Turner's syndrome who had chest pain lasting for more than 45 min accompanied by ST elevations of 0.2 mV or more in leads II, III, aVF and V1-V5. Pain disappeared within an hour and the ST segments became isoelectric. Severe back and upper abdominal pain occurred 24 hours later. Computed tomography revealed an aortic dissection from the aortic valve to the descending aorta. Intraoperatively the rupture was found to extend to an apparently single left coronary ostium. The aortic valve was bicuspid and incompetent. After aortic valve replacement, resection of the ascending aorta and implantation of a vascular prosthesis the patient's condition gradually improved and she was discharged from hospital.

Are admission plasma fibrinogen levels useful in the characterization of risk groups after myocardial infarction treated with fibrinolysis?

The aim of our study was to prove or disprove the independent prognostic importance of fibrinogen after myocardial infarction. Plasma fibrinogen levels were determined on admission in 135 patients with an acute myocardial infarction and symptoms up to 4 h (mean: 1.8 h) immediately before starting fibrinolytic treatment with 1.5 mio U. streptokinase i.v. All patients were free from other diseases which are known to cause elevated fibrinogen levels. Coronary angiography was carried out in 87%. During a mean follow-up period of 26.2 months 31 coronary events could be observed in 26 patients: 18 reinfarctions, 6 cases of sudden death, and 7 coronary artery bypass graft surgeries because of new symptoms. While plasma fibrinogen levels were higher in smokers than in non-smokers (3.30 vs 2.94 g/l p = 0.011) and correlated with the number of involved coronary arteries (p = 0.08), values were similar in patients with and without coronary events during follow-up (3.07 vs 3.16 g/l, p = 0.70). This applied as well to univariate analysis as to multivariate Cox's regression model. We conclude that plasma fibrinogen levels determined very early in patients with acute myocardial infarction do correlate with other important prognostic variables, but have no independent prognostic importance.

Apolipoprotein A and prognosis after myocardial infarction in non-diabetic men.

The implications of apolipoproteins A-I and A-II for the prognosis of 178 non-diabetic men after acute myocardial infarction were studied. During a mean follow-up period of 4 years, one or more "coronary events" (nonfatal myocardial infarction, fatal coronary heart disease, coronary artery bypass graft surgery, deterioration of exercise ECG) were recorded in 37 patients. Serum levels of apolipoproteins A-I and A-II did not discriminate between patients with and without coronary events. This applied to the entire sample as much as to subgroups defined by presence or absence of interventions (coronary artery bypass graft surgery, long-term therapy with beta-blockers or lipid-lowering drugs). We conclude that coronary events in the first years after myocardial infarction cannot be predicted by apolipoprotein A-I or A-II levels.

Long-term prognosis of patients with silent ischemia, symptomatic ischemia and without ischemia after acute myocardial infarction.

The prognosis of 55 patients with silent ischemia (group I: asymptomatic ST segment depression of greater than or equal to 0.1 mV on symptom-limited ergometer exercise) was compared with that of 25 patients with angina and ST depression (group II), 22 patients with angina but without ST depression (group III) and 94 patients without angina and without ST depression (group IV) on ergometer testing in the first post-infarction month. Patients for whom PTCA or coronary artery bypass graft surgery was planned for the next months following discharge were excluded. Groups were well matched in terms of age, sex, diabetes, non-Q-wave infarctions and global left ventricular function, but groups I and II had more inferior wall infarctions (76% and 68% respectively) than groups III and IV (18% and 34%, p less than 0.0001). After a mean follow-up time of between 26 and 33 months 11% in group I, 16% in group II, 14% in group III, but only 6% in group IV had died from cardiac disease or reinfarcted (p = 0.06). Using Cox's model, the Killip index, presence of non-Q-wave infarction, maximal ST depression on ergometer exercise and global left ventricular ejection fraction were found to be important prognostic variables affecting reinfarction-free survival, whilst angina was not. Results suggest that the presence or absence of angina as an isolated symptom is not of prognostic important after acute myocardial infarction, in comparison with objectively determinable parameters.

Iatrogenic left main coronary artery stenosis following aortic valve replacement.

A case of severe iatrogenic fibrous left main coronary artery stenosis following aortic valve replacement (Hall-Kaster prosthesis) is documented clinically, angiographically and histologically. Reported histological data of this rare complication of valve replacement are reviewed. The onset of ischaemic symptoms in the first six months after valve replacement is highly suggestive of iatrogenic coronary artery stenosis, and urgent coronary angiography is recommended.

Actinobacillus actinomycetemcomitans prosthetic valve endocarditis.

Actinobacillus actinomycetemcomitans, a fastidious gram-negative bacillus, has been reported as the cause of prosthetic valve endocarditis in 11 patients. Two additional patients are reported and the literature is reviewed. All cases occurred greater than 1 year after implantation of the prosthesis. Six of the 13 patients had had recent dental work or had poor dentition. Three patients had received endocarditis prophylaxis. Ten of 13 were cured with antibiotics alone. Only one patient suffered from congestive heart failure, and only one had documented evidence of major systemic emboli during antimicrobial therapy. Valve replacement was necessary in only two during antimicrobial therapy. A actinomycetemcomitans should be considered as a possible etiologic agent in late prosthetic valve endocarditis, particularly when blood cultures are initially negative. A regimen of a beta-lactam antibiotic in combination with an aminoglycoside is recommended for 4-6 weeks. The excellent in vitro activity of the third-generation cephalosporins and rifampin promise new therapeutic options.

[Acute myocardial infarct in patients over 70. Results of a 2-year survey]. / Der akute Myokardinfarkt bei über 70jährigen. Ergebnisse bis zu zwei Jahren.

581 consecutive patients admitted to hospital for acute myocardial infarction between January 1983 and June 1985 were divided into two groups. Group A (286) patients were aged 70 years or over (76 +/- 4 years); those in group B (246) were 65 or younger (56 +/- 8 years). Group A patients had a significantly higher incidence of anterior-wall infarction (30% vs. 18% in group B); heart failure (55% vs. 32%); pulmonary oedema (18% vs. 6%); cardiogenic shock (17% vs. 6.5%); or rupture (6% vs. 2%). Patients of the older age group also significantly less often underwent systemic fibrinolysis (0.3% vs. 21%); coronary angiography (2% vs. 61%); percutaneous transluminal coronary angioplasty (PTCA) or aorto-coronary bypass operation (0% vs. 22%) (P = 0.00001). Among the older patient group the cumulative mortality rate during hospitalization was 26.9% vs. 11.8% in group B, after six months it was 39% vs. 15%, after 12 months 46% vs. 17%, and after 24 months 61% vs. 21% (P = 0.00001). Causes of death were comparable in the two age groups, cardiac ones predominating. Angina in NYHA classes III-IV after discharge was present in 10% of the younger but 38% among the older patients (P = 0.00001). The death rate in patients of group A was very high under conservative treatment and surviving patients had a poor quality of life. Yet both coronary artery surgery and PTCA gave demonstrably better long-term results, both as to function and survival. Therefore, patients of even this higher age should more than is the case at present be more aggressively treated with invasive diagnostic and therapeutic procedures.

[Prognostic value of symptom-limited ergometry 3 weeks after acute myocardial infarct]. / Prognostische Bedeutung einer symptomlimitierten Ergometrie drei Wochen nach akutem Myokardinfarkt.

96 patients, under 70 years of age, underwent symptom-limited (maximal) exercise testing in the 3rd week after an acute myocardial infarction when neither cardiac insufficiency, angina pectoris (post-infarction) nor malignant arrhythmias were present. A further 29 patients, who could not be exercised because of the reasons mentioned, had a significantly higher frequency of coronary events during the 14 month observation period than those patients who could be exercised (55% vs. 23%, P = 0.05). When signs of (reversible) ischaemia occurred during exercise testing (angina pectoris, ST-segment depression greater than 0.1 mV), the one-year prognosis was significantly worse than in patients having no ischaemia. By means of this test the occurrence of a "coronary event" can be forecasted with high sensitivity (92%) but low specificity (46%). Thus, the negative test ("predictive value" 94%) is suitable for recognising patients with low spontaneous risk thus sparing them from further invasive investigations.

[Peripartum cardiomyopathy--a case report]. / Peripartale Kardiomyopathie--ein Fallbericht.

Peripartum cardiomyopathy (PPCM), a disorder of heart muscle, presents with the onset of cardiac failure in the last month of pregnancy or in the first 5 postpartum months. A patient with foudroyant clinical course is presented. Despite detailed clinical investigations and postmortem examination no aetiological factor was found. Diagnostic and therapeutic possibilities are discussed.