[Diagnosis of pulmonary hypertension by pulsed Doppler echocardiography--comparison with cardiac catheterization]

31 patients undergoing diagnostic cardiac catheterization for suspected congenital heart disease and 30 normal subjects were examined by pulsed Doppler echocardiography. Spectrum analysis of the shape of flow velocity curve and instantaneous flow velocities of the pulmonary artery during systolic period was made and their ratio calculated. The results showed that there was a remarkable difference between the flow velocity curve of pulmonary hypertension (PH) and that of normal pulmonary pressure. Combining with the characteristics of pulmonary arterial hemodynamics, a preliminary exploration was made on the mechanism of flow velocity curve changes. A ratio of flow velocities--PV% was proposed. The sensitivity and specificity for diagnosing PH with PV% were 94% and 100% respectively. There was a high correlation between PV% and pulmonary artery systolic pressure (r = -0.84) or pulmonary artery mean pressure (r = -0.82). It is concluded that PV% may eliminate many factors that influence the pulmonary artery hemodynamics and is a reliable, practical qualitative and quantitative index for diagnosing PH noninvasively.

Secondary structure analysis of adenovirus tripartite leader

RNA secondary structure analysis was performed to understand the translation function of the adenovirus tripartite leader, a 200-nucleotide 5' noncoding region found on all late viral mRNAs. The tripartite leader facilitates the translation of viral mRNAs at late but not early times after infection and eliminates the normal requirement for the eukaryotic initiation factor 4F or cap binding protein complex. Secondary structures were determined by probing 5' or 3' end-labeled tripartite leader RNAs under nondenaturing conditions with various single strand-specific nucleases, and the information was used to generate a potential model structure. The resulting structure is attractive since it may explain the unusual translation behavior conferred by the tripartite leader. We demonstrate that the first leader segment is predominantly single-stranded, a property consistent with the ability to enhance translation and provide independence from cap binding protein complex. In contrast, the remaining two leader segments form a moderately stable base-paired structure, except for a large hairpin loop. To confirm these findings, the secondary structure of the tripartite leader was also probed when it was attached to a large segment of a messenger RNA and was found to be very similar to that of the individual leader RNA. These findings suggest several possible mechanisms to account for the translation activity of the tripartite leader.

[Identification of Mycobacteria and measurement of whole cell fatty acids using a gas chromatography computer system]

The technique of combination gas chromatography with computer used in measuring fatty acids of 28 species standard Mycobacteria was introduced in this study. The data of components of fatty acids in this genus and GC graphs with satisfaction were gained. Several peaks with good reproducibility were distinguished automatically, based on which, M. tuberculosis, M. bovis and other comment atypical Mycobacteria may be separated respectively. It was showed that this method have the characteristics of accurate, sensitive and rapid by means of the identification of clinical strains, also have certain practical value in clinical laboratory.

Oxidative and non-oxidative mechanisms in the inactivation of cardiac mitochondrial electron transport chain components by doxorubicin

The quinonoid anthracycline, doxorubicin (Adriamycin) is a potent anti-neoplastic agent whose clinical use is limited by severe cardiotoxicity. Mitochondrial damage is a major component of this cardiotoxicity, and rival oxidative and non-oxidative mechanisms for inactivation of the electron transport chain have been proposed. Using bovine heart submitochondrial preparations (SMP) we have now found that both oxidative and non-oxidative mechanisms occur in vitro, depending solely on the concentration of doxorubicin employed. Redox cycling of doxorubicin by Complex I of the respiratory chain (which generates doxorubicin semiquinone radicals, O2-, H2O2, and .OH) caused a 70% decrease in the Vmax. for NADH dehydrogenase during 15 min incubation of SMP, and an 80% decrease in NADH oxidase activity after 2 h incubation. This inactivation required only 25-50 microM-doxorubicin and represents true oxidative damage, since both NADH (for doxorubicin redox cycling) and oxygen were obligatory participants. The damage appears localized between the NADH dehydrogenase flavin (site of doxorubicin reduction) and iron-sulphur centre N-1. Succinate dehydrogenase, succinate oxidase, and cytochrome c oxidase activities were strongly inhibited by higher doxorubicin concentrations, but this phenomenon did not involve doxorubicin redox cycling (no NADH or oxygen requirement). Doxorubicin concentrations of 0.5 mM were required for 50% decreases in these activities, except for cytochrome c oxidase which was only 30% inhibited following incubation with even 1.0 mM-doxorubicin. Our results indicate that low concentrations of doxorubicin (50 microM or less) can catalyse a site-specific oxidative damage to the NADH oxidation pathway. In contrast, ten-fold higher doxorubicin concentrations (or more) are required for non-oxidative inactivation of the electron transport chain; probably via binding to cardiolipin and/or generalized membrane chaotropic effects. The development of agents to block doxorubicin toxicity in vivo will clearly require detailed clinical studies of doxorubicin uptake in the heart.

Increased content of a minor ankyrin in erythrocyte membranes of bipolar subjects

This preliminary study reports on the increased content of a structurally important protein in erythrocyte membranes of bipolar patients treated with lithium carbonate compared with control subjects. The external portion of the erythrocyte membrane is a lipid bilayer into which various integral proteins are inserted; some of these serve as ion channels or energy-dependent transport systems. Another group of proteins, including those termed "ankyrins," link the bilayer to an underlying network of cytoskeletal proteins, and maintain both cell shape and the arrangement of integral proteins within the bilayer. Structural changes resulting from the observed excess of one of the ankyrins in membranes from bipolar subjects could alter several aspects of membrane function. Ankyrins also occur in neurons, where a corresponding increase would alter central nervous system function.

[Thin-layer chromatography of mycolic acids methanolysates of whole-cell in Mycobacterium and related bacteria]

Mycolic acid methanolysates of whole-cell in Mycobacterium and related bacteria were analysed by thin-layer chromatography. The experimental results show that five of twenty-two species, M. tuberculosis, M. bovis, M. kansasii, M. marinum and M. gastri have similar pattern of mycolates, composed of alpha-mycolates, methoxymycolates, ketomycolates and two unknown components. M. gilvum, M. phleri, M. avium, M. intracellulare, M. xenopi and M. nonchromogenicum contain alpha-mycolates, ketomycolates and wax-ester. The patterns of TLC for other tested species were different from each other. Nocardia, Rhodococcus and Corynebacterium show a relatively simple pattern which principally contain alpha-mycolates. The four genus can be differentiated. Spots of mycolic acids of nine strains Mycobacterium sp. isolated from patients in this hospital were similar to M. tuberculosis. These strains were also identified to the same result as above by traditional methods. The method is of value in the classification and identification of Mycobacterium.

The effect of edible black tree fungus (Auricuaria auricula) on experimental atherosclerosis in rabbits

The effects of edible black tree fungus (BFF) compared with aspirin on serum lipid level and experimental atherosclerosis and thrombosis in rabbits were studied. The results showed that total serum cholesterol and B-lipoprotein of the BTF group were significantly decreased (P less than 0.01) than the aspirin group and the group with neither BTF nor aspirin. There were less aortic atherosclerotic plaque and intramyocardial arterial lumen stenosis in the BTF group. The development of thrombus and platelet aggregation and thromboxane TXB2 level were inhibited both in the BTF and aspirin group (P less than 0.01). These findings indicate BTF may be used as a healthy food in preventing atherosclerosis and coronary heart disease, but its mechanism requires further investigation.

[Evaluation of coronary artery fistula using a color Doppler flow imaging technique]

Two unusual cases with coronary artery fistula were reported. The diagnoses were first made by color Doppler flow imaging and confirmed by selective coronary angiography and operation. In the first case, color Doppler revealed a continuous flow signal within the dilated left coronary artery and a turbulent jet within the right atrium. In the second case, color Doppler showed turbulent flow signals which could be traced from the proximal left coronary artery, along the left ventricular posterior wall and into the left ventricle. The high velocities at the site of drainage of fistula were recorded by the continuous-wave Doppler and the calculated pressure gradient confirmed that the abnormal flow was from the systemic circulation. We are of the opinion that color Doppler flow imaging is a reliable technique for detecting coronary artery fistula and the combination of color Doppler with continuous-wave Doppler is essential for evaluating the hemodynamics of the shunt flow.

Motor unit power spectrum and firing rate

Changes in the power density spectrum of myoelectric signal with contraction level have been reported in the literature. These changes can be induced by a number of possible factors including recruitment of differing types of units, conduction velocity changes and firing rate changes. In the paper the single unit power spectrum is investigated and the effects of firing rate mean and variance changes evaluated. Motor unit signal simulation and experiments are carried out to verify predictions. The results show that spectrum peaks will shift with firing rate and the median frequency is weakly dependent on firing rate.

Heterogeneity of fast-oxidative muscle fibers of chicken demonstrated by anti-myosin monoclonal antibodies

The fiber type composition of two fast muscles of the chicken, namely, adductor superficialis (AS) and pectoralis major (PM) was examined by the histochemical myosin ATPase staining and immunochemical techniques using monoclonal antibodies (McAbs). Two new McAbs produced against the myosin of the anterior latissimus dorsi (ALD) muscle of the chicken and named ALD-122 and ALD-83 were characterized to be specific for myosin heavy chain (MHC) and for myosin light chain-1 respectively. They were used in conjunction with previously reported McAbs specific for slow MHC (ALD-47), fast MHC (MF-14) and fast light chain-2 (MF-5). By the histochemical ATPase test most muscle fibers of AS and PM muscles reacted as IIA and IIB respectively. By immunofluorescent staining with the anti-MHC McAbs, ALD-122 and MF-14, the fibers of AS muscle showed remarkable heterogeneity whereas PM muscle fibers reacted uniformly. Differences in the myosin light chain composition of AS and PM muscles were also found by SDS-gel electrophoresis and immunoblot analysis with the anti-light chain McAb, ALD-83. The study clearly indicated that the histochemically homogenous (type IIA) AS muscle is composed of several subpopulations of fibers which differ in their myosin composition and that this heterogeneity of the muscle is not simply due to presence of variable amounts of slow myosin in its fibers.

Antimalarial properties of ebselen

The seleno-organic compound ebselen showed anti-malarial activity in vitro against the murine Plasmodium berghei and the human P. falciparum. In P. berghei, the uptake and incorporation of [3H]-methionine and [3H]-adenosine was inhibited and the infectivity of plasmodia was reduced. Ebselen affects the development of asexual stages of chloroquine-resistant and -sensitive P. falciparum strains. Its IC50 for P. falciparum was about 14 mumol/l and that for P. berghei, about 10 mumol/l. The growth of P. falciparum was blocked by ebselen at all stages, including the invasion of erythrocytes by merozoites. In a human hepatoma cell line and in mouse peritoneal macrophages, no cytostatic or cytotoxic effects were found, indicating selective inhibition of plasmodia by ebselen. Its in vitro inhibitory effect is discussed in relation to its possible reactivity with thiol groups and its lack of an anti-malarial effect in infected mice.

Determination of Settings of a Tilted Head Cutter for Generation of Hypoid and Spiral Bevel Gears

Kinematics of mechanisms of hypoid and spiral bevel cutting machines is considered. These mechanisms are designated to install the position and tilt of the head cutter. The tilt of the head cutter with standard blades provides the required pressure angle. The authors have developed the matrix presentation of kinematics of these mechanisms and basic equations for the required settings. An example is presented based on the developed computation procedure.

Mitochondria contain a proteolytic system which can recognize and degrade oxidatively-denatured proteins

When incubated with mitochondria in an air atmosphere, menadione and doxorubicin (which redox cycle with the respiratory chain to produce oxygen radicals), as well as xanthine oxidase plus xanthine (which generate superoxide and H2O2), stimulated the degradation of newly-synthesized [( 3H]leucine-labelled) mitochondrial polypeptides. No stimulation was observed in an N2 atmosphere, ATP was not required, and xanthine oxidase was not effective without xanthine. Various forms of oxidative stress induced varying degrees of protein cross-linking, protein fragmentation and proteolysis, as judged by gel electrophoresis and amino acid analysis. To learn more about the proteolytic enzymes involved in degradation, we undertook studies with purified protein substrates which had been exposed to oxidative stress (OH or H2O2) in vitro. Despite mitochondrial contamination with acid proteases of lysosomal (and other) origin, pH profiles revealed distinct proteolytic activities at both pH 4 and pH 8. The pH 8 activity preferentially degraded the oxidatively-denatured forms of haemoglobin, albumin and superoxide dismutase; was unaffected by digitonin; and exhibited a several-fold increase in activity upon mitochondrial disruption (highest activity being found in the matrix). In contrast, the pH 4 activity was dramatically decreased by digitonin treatment (to reduce lysosomal contamination); was unaffected by mitochondrial disruption; and showed no preference for oxidatively-denatured proteins. The pH 8 activity was not stimulated by ATP, but was inhibited by EDTA, haemin and phenylmethylsulphonyl fluoride. In contrast, the contaminating pH 4 activity was only inhibited by pepstatin and leupeptin. Thus, our experiments reveal a distinct mitochondrial (matrix) proteolytic pathway which can preferentially degrade oxidatively-denatured proteins.