Nature and properties of secondary structures formed during fretting corrosion

Conclusions The secondary structures formed in the surface layers of a materlal during fretting corrosion consist of nonmetallic phases — oxides of the principal metallic element and solutions of variable concentration of oxygen or the principal metallic element based on these oxides.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 25–27, August, 1978.     

Evidence for soluble and nuclear site I binding of estrogens in human aorta

The purpose of this study was to establish the estrogen receptor (ER) expression and content in human aorta fragments removed at the time of by-pass surgery. To this end, we adopted a radioligand binding assay to evaluate either soluble (S) or nuclear (N) ER using dextran-coated charcoal (DCC) and filtration methods, respectively. To better define the intratissular distribution and content of ER, we also measured the presence of a 27 kDa heat shock protein (HSP27), a well established ER-associated protein, using D5 monoclonal antibody. Finally, we analysed the different molecular isoforms of both S and N ER using size exclusion-high performance liquid chromatography (SE-HPLC). High affinity (type I) sites of estrogen binding were detected in 17 out of 19 samples in either S or N fraction, although only 9 out of 19 cases displayed site 1 ER in both cell compartments. ER levels in aortic tissues, detected by radioligand method, compare well with those we have found in other hormone-sensitive human cancer tissues and cells. SE-HPLC analysis revealed two main receptor isoforms in the soluble fraction, having 65 kDa and 18 kDa molecular mass, while a minor component of 29 kDa was also found; the nuclear fraction displayed again two major components of 38 and 23 kDa. Using the HSP27 immunohistochemistry we observed a major staining occurring in smooth muscle cells (SMC), with an increasing intensity towards the lumen. All samples, including the ER negative ones, exhibited some degree of histochemical staining. Using an arbitrary cut-off value, 7 out of 12 samples displayed a highly positive staining, 6 of which showed nuclear ER. Furthermore, SE-HPLC separation indicated the presence of a 64.9 kDa component in the soluble fraction, according to the well known relative molecular mass of ER. Following HSP27 immunohistochemistry, the overall staining intensity in aortic SMC approaches that seen in endometrial and breast epithelia, whilst the muscle ER content is generally lower. Although our data are compatible with a direct role of estrogens in arterial function, the extent of the link with arterial disease remains to be established.     

Microprocessor-based portable system for heart condition diagnosis

Early diagnosis of heart disease is typically based on a cassette recording of the electrocardiogram (ECG) signal which is then studied and analysed using a microcomputer. The system is bulky, unreliable and prone to mechanical failure. This paper presents the design and implementation of a compact microprocessor-based portable system used for heart condition diagnosis over a long period. The system reads, stores and analyses the ECG signals repetitively in real time for a specified period. The diagnostic data and samples of ECG signals are stored throughout the test period. The system hardware and software design are oriented towards a single-chip microcomputer-based system, hence minimizing size. The operating algorithm is based on a logical approach to ECG signal diagnosis and hence requires little memory.     

Function of the residual myocardium after infarct and prognostic significance

Changes of the left ventricle after myocardial infarction are characterized by geometric, structural, and vascular alterations, which have been summarized under the term "remodeling". This process takes place in the infarct region as well as in the surviving myocardium. Depending on to the size of infarction and the degree of neurohumoral activation, the left ventricle demonstrates diastolic dysfunction which may finally lead to systolic failure. The residual myocardium develops progressive myocyte hypertrophy and interstitial fibrosis. These structural alterations are due to changes in loading conditions and stimulation of the neurohumoral system with an activation of local paracrine and autocrine factors. Myocardial function can be assessed by different non-invasive (echocardiography, radionuclide ventriculography, magnetic resonance imaging, etc.) or invasive methods (e.g., simultaneous pressure-volume measurements). "Myocardial tagging" based on magnetic resonance imaging allows the assessment of 3D-motion of the left ventricle by labelling specific myocardial regions with a rectangular grid. A systolic "wringing" motion with clock-wise rotation at the base and counter-clockwise rotation at the apex has been described in normal subjects. In the ischemic myocardium, delayed relaxation with a prolonged back-rotation (untwisting) has been reported during early diastole, whereas decreased systolic contraction with delayed diastolic rotation has been observed in non-Q-wave infarction. In patients with anterolateral aneurysms, a complete loss of systolic rotation has been demonstrated. The prognostic significance of LV "remodeling" has been emphasized by several authors: The size of infarction, LV volume, LV ejection fraction, as well as the degree of neurohumoral activation have been identified as being associated with an unfavorable clinical outcome. Yearly mortality rates have been reported to range between 15 and 17% in patients with large infarcts and marked LV dilatation and between 3 and 7% in patients with small to medium-sized infarcts.     

Effect of inflammation on the proliferation of human gingival epithelial cells in vitro

The adaptive or pathologic responses of epithelial cells to inflammation are poorly characterized. The purpose of this study was to determine if epithelial cells cultured from clinically healthy and inflamed human gingival tissues express differences in proliferation rate and viability. Briefly, the inflammation status of individual donor sites from 101 patients was visually assessed at the time of periodontal surgery and categorized as either non-to-slightly inflamed, moderately inflamed, or severely inflamed. Discarded gingival tissues were then processed to obtain primary cell cultures, for which proliferation rates were determined by calculating the ratio of mean population doublings to the number of days required for cultures to become confluent. In general, the cells in the minimally inflamed group exhibited characteristics different than cells in the moderately and severely inflamed groups. Specifically, the cells obtained from clinical sites which exhibited no-to-slight inflammation had a significantly higher mean proliferation rate than cells in either the moderate inflammation group or the severe inflammation group. Based on trypan blue exclusion, the cells obtained from clinical sites which exhibited no-to-slight inflammation also were more viable than cells obtained from sites with moderate inflammation or severe inflammation. Microscopic evaluation showed morphological changes associated with increased inflammation. Cell cycle analysis by fluorescent-activated cell sorting (FACS) revealed a directly proportional relationship between the degree of inflammation and apoptosis, and a strong inversely proportional trend between the degree of inflammation and the numbers of cells undergoing mitosis. Taken together, these data suggest that epithelial cell proliferation and viability are inversely associated with the degree of gingival inflammation, once a putative "adaptive threshold" is exceeded. Elucidation of the underlying mechanisms will likely lead to improvements in clinical diagnosis and treatment.     

Sotahexal pharmacodynamics in patients with ischemic heart disease

Therapeutic and prophylactic antiarrhythmic efficacy of sotalol hydrochloride (Sotahexal, "Hexal", Germany) and its effects in intracardiac hemodynamics and ECG parameters were evaluated in 95 patients with ischemic heart disease (IHD). The highest response to the drug was observed in ventricular extrasystoles, arterial flutter and fibrillation. Acute episodes of arrhythmia are managed by bolus administration of Sotahexal [correction of Hexal]. In this case greater risk of side effects exists. It is desirable to decide on the drug dose, mode of administration on the individual basis with due consideration of the risks and dangers which could be avoided in case of adequate instrumental control.     

Reduced epicardial coronary vasodilator capacity in patients with left ventricular hypertrophy

BACKGROUND: Enlargement of the epicardial coronary arteries occurs in left ventricular (LV) hypertrophy as an adaptation to the increased coronary blood flow. METHODS AND RESULTS: Vasodilator capacity of the epicardial coronary arteries was determined in 44 patients. The dose-response relation of intracoronary nitroglycerin was assessed in 14 patients (7 control subjects and 7 patients with aortic stenosis [study A]) using quantitative coronary angiography. In a second study (B), vasodilator capacity of the epicardial coronary arteries was determined in 15 control subjects and 15 patients with valvular heart disease. In study A, a curvilinear dose-response relation with maximal vasodilation after 90 micrograms intracoronary nitroglycerin was found in both control subjects and patients with aortic stenosis. Vasodilator capacity was reduced in those with aortic stenosis, although sensitivity to nitroglycerin was similar in both groups. In study B, coronary circumferential length at baseline was larger in those with LV hypertrophy (12.2 +/- 2.2 mm) than in control subjects (8.6 +/- 1.5 mm; P < .001); after 100 micrograms intracoronary nitroglycerin, it increased to 12.9 +/- 2.2 mm (6 +/- 5%) in those with LV hypertrophy and to 10.3 +/- 1.5 mm (21 +/- 8%; P < .001) in control subjects. An inverse relation between baseline circumferential length and its percent increase after nitroglycerin was found (r = -.71, P < .001). CONCLUSIONS: Vasodilator capacity of the epicardial coronary arteries is reduced in patients with LV hypertrophy, although sensitivity to nitroglycerin is normal. This may be due to a flow-mediated decrease in coronary vasomotor tone and/or the occurrence of vascular remodeling with an enlargement of the coronary arteries.     

Reactions of bovine liver catalase with superoxide radicals and hydrogen peroxide

The oxidized intermediates generated upon exposure of bovine liver catalase to hydrogen peroxide (H2O2) and superoxide radical (O2-) fluxes were examined with UV-visible spectrophotometry. H2O2 and O2- were generated by means of glucose/glucose oxidase and xanthine/xanthine oxidase systems. Serial overlay of absorption spectra in the Soret (350-450 nm) and visible (450-700 nm) regions showed that three oxidized intermediates, namely Compounds I, II and III, can be observed upon exposure of catalase to enzymatically generated H2O2 and O2-. Compound I is formed during the reaction of native enzyme with H2O2 and disappears in two ways: (i) via the catalytic reaction with H2O2 to restore native catalase and (ii) via the reaction with O2- to form Compound II. At low H2O2 concentrations (< 4.8 x 10(-9) M H2O2), Compound II reverts towards the native state mainly in a direct one-step reaction, whereas at higher H2O2 concentrations the pathway of Compound II back to the native enzyme involves Compound III. Formation of the latter from Compound II and H2O2 is irreversible and the rate constant of this reaction is 6.1 +/- 0.2 x 10(4) M-1 s-1. The formation of Compound III through the direct reaction of O2- with native enzyme has also been observed. Depending on the experimental conditions, the inactivation of catalase by O2- can be due to accumulation of Compound II ("slow" inhibition) or to the formation of Compound III ("rapid" inhibition) part of which leads to a dead end product. Formation of Compound III and of this dead end product are responsible for the irreversible inactivation in presence of an excess of H2O2.