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PubMed1981

[Determination of the systolic time interval in normal subjects from electrokymographic studies of vessels near the heart].

By means of electrokymography curves of the motion of the vascular margin of the large vessels near the heart, aorta and pulmonary artery, may be recorded noninvasively. Since these curves of motion widely correspond to the central curves of the arterial pulse it is possible to state systolic time intervals separately for the right and left heart. Analogically to the presphygmic index after Rentsch with global evidence on the left-ventricular function of the heart these are possible for the outflow way of the right ventricle, also by formation of the quotient of the electrokymographically established STI. Comparisons between right-ventricular and left-ventricular STI and relations to the at the same time electrokymographically stated dynamic parameters of the heart wall are the result. In the present paper on the basis of electrokymographical investigations on 24 test persons with healthy heart the concerning the contents reasonable STI with relatively slight statistical distribution and their quotient are determined as starting-point to further investigations.

Aorta↗
PubMed1981

[Mercury and methylmercury pollution of fishery products. Toxicological effects on human health (author's transl)].

Since the japanese mass poisoning in 1954's, classically named today "Minamata disease", mercury and its derivatives occupy a place of choice into the most worrying chemical pollutants for the human health and a lot of studies about the pathways by which mercury enters in its biogeochemical cycle or the environmental mercury levels are resumed in this paper. The most important aspects of mercury ecotoxicology are reviewed here: biological methylation reaction, bioaccumulation and biomagnification of these toxics in te aquatic ecosystems. The authors also describe the mercury and methylmercury metabolism and the symptomatology of the methylmercurial poisoning; with emphasis that infraclinic chronical manifestations, or large epidemiological interest, are not well known. It should be necessary to found a sensitive biochemical test, specific of this intoxication. The studies about the initial body burden assessment or the threshold values of mercury in easily obtainable specimens (blood hair) are only available for a statistical distribution. At individual levels, a number of factors occur, particularly the presence of selenium who should act as a biological antagonist of methylmercury.

Animals↗
PubMedDate not supplied

[Inclusion compounds of collagen (author's transl)].

Small angle X-ray diagrams of collagen of rat tail treated with phospho tungstic acid or mercury chloride or cobalt- and uranyl-nitrate, osmiumoxide or hydroxy apatite show the same characteristic new reflections and reflection lines. The only remarkable difference exists between fibers treated under stress or relaxed. These experiments give new evidence for the paracrystallinity of collagen. More than 100 parallel aligned ca. 40 A thick octafibrils consist of 670 A long microparacrystals with 5 ca. 25 A thick soft segment layers. In these soft segments the holes of the octafibrils build up a lattice of vacancies with lattice cells of 38,5 x 35 x 135 A3 length. The above mentioned molecules penetrate from the lateral sides through the soft segments into these vacancies building up complexes with peptide groups of collagen. Under stress only a small amount of vacancies is occupied, statistically distributed over the vacancy-lattice, because the soft segments of the octafibrils are constricted. Without stress about 10 to 25% of the octafibrils within one paracrystal are filled up with sediments in the soft regions. With increasing precipitation finally 500 A long needles are formed of the inclusive material as detected by Höhling with the electron microscope in collagen of turkey tendon. The importance of the paracrystalline collagen model is emphasized to understand the biological process like the mineralisation of collagen and beta-keratin in organism or the activity of bone apatite in exchanging calcium ions.

Amino Acid Sequence↗
PubMed1980

Morphological studies of cultured human pulmonary macrophages.

A morphological classification scheme is developed for the quantitative in vitro examination, by scanning electron microscopy (SEM), of pulmonary alveolar macrophages (AM) from human cigarette smokers and nonsmokers. The AM were obtained by bronchopulmonary lavage, allowed to attach to glass coverslips in a serum containing medium, cultured for 1, 2, or 25 hours, and examined in the SEM. Fifty cells per sample were randomly selected for detailed morphological analysis using a predetermined sampling grid. Area, form, degree of cell spreading, and the relative abundances of surface features, including ruffles, filopodia, blebs, microvilli, multiple features, and no surface features were quantified. Smoker AM had a greater incidence of ruffles, filopodia, multiple features, and rounded cells; nonsmoker AM had greater incidences of featureless and spread cells. Microvilli and blebs were observed infrequently and displayed no trends with respect to differences between smokers and nonsmokers. The incidence of filopodia, multiple features, and intermediate shapes generally increased with increasing culture time, and a decreasing incidence with increasing time in culture was observed for featureless and spread cells. For the 1- and 2-hour culture periods, slightly greater sizes, size variances, form factors, and form factor variances were observed for smoker AM; however, after 25 hours in culture, nonsmoker AM populations possessed these characteristics. Area frequency distributions appeared to be logarithmically normal in distribution. Statistical analyses indicated that for area and form, the greatest variance was due to variations among the individuals lavaged.

Cell Adhesion↗
PubMed1994

[A position effect variegation model of chromatin compaction].

A position effect variegation (PEV) model of chromatin compaction is proposed, based on the concept of a statistical distribution of compaction protein (CP) molecules around compaction initiation centers (CICs). The principles of the model are as follows: (1) CICs are present in both hetero- and euchromatin, and (2) different CP molecules interact not only with DNA but also with one another, forming a multimeric complex. When a certain level of DNA-protein binding is exceeded, heterochromatic domains are formed. The model suggests that continuous and discontinuous chromatin compaction resulting from PEV is due to an irregular CIC distribution along the chromosome.

Animals↗
PubMed1993

[The action of atracurium and vecuronium in chronically hemodialyzed patients].

UNLABELLED: Reports on the duration of action of atracurium (Atr) and vecuronium (Vec) in patients with renal failure are contradictory. It is either stated that the duration is equal for both relaxants or that Atr acts for a longer duration. Because of these conflicting results, we measured the times for latency (tL), onset (tA), duration of action (tW), and recovery (tE) for both agents. METHODS: Fourty patients with end-stage renal failure on chronic haemodialysis were randomly assigned to receive either Atr (0.4 mg.kg-1 BW) or Vec (0.08 mg.kg-1 BW). After induction with thiopentone and 0.1 mg fentanyl, anaesthesia was maintained with nitrous oxide and 1 vol.% ethrane and expiratory CO2 partial pressure was kept between 4.6 and 4.9 kPa. If the twitch height of T1 regained 25% of the pre-relaxation value, 20% of the initial relaxant bolus was injected. Relaxation was monitored with a relaxograph after calibration of the device. After testing for a normal distribution, statistical analysis was done by Student's t-test. A value of P < or = 0.05 was chosen for statistical significance. RESULTS: There were no significant differences regarding tL (Atr: 1.0 +/- 0.5 min; Vec: 1.1 +/- 0.5 min) and tA (Atr: 5.5 +/- 2.1 min; Vec 4.1 +/- 2.4 min); tW (Atr: 21.3 +/- 13.1 min; Vec 31.7 +/- 15.6 min) and tE (Atr: 19.0 +/- 9.0 min; Vec 30.1 +/- 19.0) were significantly different. DISCUSSION: Our results are not in accordance with those authors who found in comparison with Atr an equal or shorter duration of action for Vec in patients with renal failure. If the duration of action is equal in subjects with no renal insufficiency, our measurements are in accordance with kinetic evaluations showing the same clearance and half-life for Atr in patients with and without renal insufficiency, but 40% diminished clearance and 60% prolonged half-life for Vec in renal insufficiency.

Adult↗
PubMed1993

The formation of the haemostatic plug--a special case of platelet aggregation. An experiment and a survey of the literature.

The formation of the haemostatic plug is an extremely fast process. This excludes, at least in its first phase, the involvement of soluble activating agents released from or produced by the platelets. An experiment with ADP-activated, formaldehyde-fixed platelets shows that platelets with activated fibrinogen receptors will bind inactive platelets in the presence of fibrinogen and Ca(2+)-ions. A survey of the literature shows that platelet activation is accompanied by the clustering of the fibrinogen receptors. The surface of an activated platelet, which makes part of the growing haemostatic plug therefore is covered with patches of tightly packed fibrinogen. This allows the multisite combination with the statistically distributed low affinity receptors of the newly arriving platelets. Tightly packed fibrinogen, as present on clusters of the activated GP IIb/IIIa receptors as well as when absorbed to artificial surfaces acts as an activator of platelets. Thus, the propagation of the activation process is possible without a requirement for other, external activators. Such agents, which are released from platelets and, finally, thrombin formation, are nonetheless of vital importance, not for the formation but for the consolidation of the haemostatic plug.

Adenosine Diphosphate↗
PubMed1976

[Microspectrometric quantification of 4-hydroxypentenal binding to protein thiols in Ehrlich ascites tumor cells].

After 30 minutes in 5.10(-3) M hydroxypentenal (HPE) the microscopically determinable proteinthiols (PSH) stained with DDD-Fastblue B decrease from 1,07 . 10(-14) to 0,61 . 10(-14) moles/cell. The loss of PSH of 0,46 . 10(-14) moles has a confidential range (99%) of +/- 0,12. As HPE reacts with thiols by an addition to the C3 = C2-group, the aldehydic group remains reactive and can be recognized intracellulary and quantitatively determined with 2,4-dinitrophenylhydrazine, whereby an uptake of 0,63 . 10(-14) moles of HPE per single cell is observed (confidential range +/- 0,11). The broad overlapping of the confidential ranges indicates clearly that the loss of PSH corresponds to the uptake of HPE. From the statistical distribution diagrams it can be seen that the PSH of practically all cells take part in the reaction, if however, to very different extent; the cells with high PSH concentrations being the most reactive ones.

Aldehydes↗
PubMed1997

Proposal of reference values for home blood pressure measurement: prognostic criteria based on a prospective observation of the general population in Ohasama, Japan.

The purpose of this study was to propose reference values, from a viewpoint of prognostic significance, for blood pressure (BP) measured at home with a semiautomated device (home BP measurement) to differentiate normotension and hypertension. We obtained home BP measurements for 1,913 population-based subjects aged 40 years and over in a rural Japanese community and followed up their survival for a mean duration of 5.0 years. There were 141 deaths during the follow-up period. The association between baseline BP values and the overall mortality was examined by Cox proportional hazards regression model, adjusted for age, gender, and the use of antihypertensive medication. The results indicated that the predictive power of home BP level for subsequent mortality was stronger than that of casual screening BP. There was a linear association between home systolic BP and mortality. The association between home diastolic BP and mortality was nonlinear and well approximated with the secondary degree equation of diastolic BP values. Based on this relation, we propose that the reference value for hypertension is 137/84 mm Hg, and normotension is below 137 mm Hg for home systolic BP and between 66 and 83 mm Hg for home diastolic BP. Home diastolic BP below 66 mm Hg should be considered as low diastolic blood pressure. In this population, home systolic BP of 137 mm Hg and home diastolic BP of 84 mm Hg corresponded to the 80th and 87th percentiles, respectively. Then, 29% of the subjects were classified as having hypertension, 52% as normotension, and 19% as low diastolic blood pressure. All previous studies proposing reference values for home BP measurement, derived from cross-sectional observations, were based on the statistical distribution of home BP values. The reference value must, however, be the one that best predicts the risk for morbidity and mortality from hypertension-related complications. This is the first report proposing reference values for home BP measurement based on prognostic criteria.

Adult↗
PubMed1997

Quantitative ultrastructural analysis of hippocampal excitatory synapses.

From three-dimensional reconstructions of CA1 excitatory synapses in the rodent hippocampus and in culture, we have estimated statistical distributions of active zone and postsynaptic density (PSD) sizes (average area approximately 0.04 micron2), the number of active zones per bouton (usually one), the number of docked vesicles per active zone (approximately 10), and the total number of vesicles per bouton (approximately 200), and we have determined relationships between these quantities, all of which vary from synapse to synapse but are highly correlated. These measurements have been related to synaptic physiology. In particular, we propose that the distribution of active zone areas can account for the distribution of synaptic release probabilities and that each active zone constitutes a release site as identified in the standard quantal theory attributable to Katz (1969).

Animals↗
PubMed1997

Description of the ventriculoarterial interaction dynamics using recurrence plot strategies.

OBJECTIVE: The classical description of ventriculoarterial coupling by calculating the ratio between the effective arterial elastance Ea to the end-systolic elastance Ees does not give insight into the underlying dynamics of the interaction between left-ventricular pressure (LVP) and aortic pressure (AOP) and flow (AOF). The aim of this study was to introduce a state space representation for the ventriculoarterial coupling and to quantify changes of the coupling state. METHODS: A ventriculoarterial state space orbit VAO was defined to be dependent on three variables: VAO = [LVP(t), AOP(t + delta t), AOF(t + delta t)]. Changes in the coupling effect directly or indirectly on the time series of these parameters. They reflect the actual state of the cardiovascular system. The time delay delta t between the LVP and the aortic signals takes respect to the short delay between the heart action and the resulting waves in the arterial tree. The recurrence map of the VAO(i) (i = 1 .. N, N = number of points) is constructed by plotting the index i of every single point on the orbit (x-axis) against the indices of his 10 nearest neighbors (y-axis) in distance. The data were recorded in 9 anaesthetized pigs with a sample frequency of 512 Hz over a period of 6 seconds using piezoelectric pressure sensors and a Doppler flowmeter. A control condition was compared to a total occlusion of the descending aorta as a strong artificial disturbance of ventriculoarterial interaction. The nonlinear parameters percent recurrence, percent determinism and the entropy were calculated from the plot. RESULTS: Periodic crossing points and forbidden zones in all plots identify the nonlinear character of the chosen variables. The recurrent patterns are less rigid for control conditions than for total occlusion. Entropy (2.3% rise) and determinism (24% rise) are significantly (p < 0.003) increased. Total aortic occlusion leads to more complex time correlation patterns. CONCLUSIONS: These results may reflect the loss of an ideal coupling state leading to a more complex deterministic behavior of the overall regulatory system. Because recurrence plots do not impose rigid constraints on data set size, stationarity, or statistical distribution, we hypothesize that this technique might be useful to describe the nonlinear dynamics between left ventricle and arterial system.

Animals↗
PubMed1998

Chromatin texture signatures in nuclei from prostate lesions.

OBJECTIVE: To characterize nuclei from prostatic lesions in a highly specific manner by developing a nuclear chromatin texture signature and to characterize lesions by means of their composition of nuclei with diverse degrees of deviation from normal. STUDY DESIGN: High-resolution digitized imagery of nuclei from normal prostates, from prostatic neoplastic lesions of low and high grade and from histologically normal appearing regions of prostates with low and high grade prostatic intraepithelial neoplasia (PIN) lesions were recorded. A set of 65 features descriptive of the spatial and statistical distribution of nuclear chromatin was computed for each nucleus. These features were arranged and processed to form a distinctive signature. A distance metric from "normal" was defined and computed for each nucleus. RESULTS: Profiles of feature values can, after suitable scaling, be presented as distinctive feature value signatures. For many practical applications, profiles based on a standardized distance from normal nuclei may be more useful. Such profiles allow the derivation of a progression curve, showing increasing distances for diagnostic groups with increasing lesion progression up to high grade PIN lesions. Within each diagnostic group different cases show distinctive distributions of nuclei with differing degrees of deviation from normal, allowing the derivation of a lesion signature. CONCLUSION: Nuclear chromatin texture signatures may be of value for the characterization of both nuclei and lesions. They are based on a more comprehensive use of information offered by the nuclear chromatin pattern than that included in classification methods. While these signatures offer a more specific characterization of a clinical sample, they also are subject to more variability within a diagnostic category. This may not be due to randomness but may reflect some actual differences between lesions.

Adenocarcinoma↗
PubMed1999

Percent cholesterol absorption in normal women and men quantified with dual stable isotopic tracers and negative ion mass spectrometry.

Percent cholesterol absorption was measured in 94 normal subjects aged 17- 80 years while consuming diets generally low in cholesterol (mean intake = 226 +/- 126 mg/day). A new dual stable isotope method was used where a cholesterol tracer containing 6 extra mass units was given intravenously and another tracer with 5 extra mass units was given orally during a standard test meal. The ratio of tracers in plasma was determined by negative ion mass spectrometry of pentafluorobenzoyl sterol esters. Absorption values ranged widely from 29.0% to 80.1% with mean 56.2 +/- 12.1 (SD) %. Cholesterol absorption was significantly increased in African-Americans (63.4 +/- 11.8% vs. 55.1 +/- 11.9%, P = 0.027) but was similar for women (53.3 +/- 11.9%) and men (57.6 +/- 12.1%). It was not related to plasma lipoproteins, age, apoE3/E3 or E3/E4 genotype, or chronic dietary intake of energy, fat, or cholesterol quantitated from 7- day food records. However, dietary cholesterol intake was positively related to plasma cholesterol (P = 0.036) and triglycerides (P = 0.026). The milligram amount of dietary cholesterol absorbed (but not percent absorption) was positively correlated with fasting plasma insulin (r = 0.525, P < 0.0001), C-peptide (r = 0.367, P = 0.0003) and glucagon (r = 0.421, P < 0.0001) independent of gender, body fat percent and age.The efficiency of intestinal cholesterol absorption and the milligram amount of dietary cholesterol absorbed were not related to plasma cholesterol or LDL cholesterol in individuals consuming a low-cholesterol low-fat diet. The dominant factor determining dietary cholesterol absorption was intake rather than absorption efficiency. Dietary cholesterol and fat were strongly and independently related to hormonal measures of insulin resistance.-Bosner, M. S., L. G. Lange, W. F. Stenson, and R. E. Ostlund, Jr. Percent cholesterol absorption in normal women and men quantified with dual stable isotopic tracers and negative ion mass spectrometry.

Adult↗
PubMed1998

The mechanism of the silent zone on Lorenz plots in atrial fibrillation.

Lorenz plot is an acknowledged method of the evaluation of sequences of ventricular beats in cardiac arrhythmias, particularly in atrial fibrillation. Lorenz plots are scatterplots that show the R-R intervals as a function of the preceding R-R intervals. The authors of this paper conducted studies of 83 cases of atrial fibrillation; histograms of 500 consecutive R-R intervals were made, determining the mean R-R interval, the functional refraction period (FRP) of AV node and Lorenz plots. In 22 cases (26.5%) the presence of the silent zone on a Lorenz plot was observed, similarly to the study of Nakatsu and al. The silent zone appeared only in cases when the statistical distribution of R-R intervals was reflected by a bimodal histogram (less frequently by a trimodal histogram). The silent zone was never observed in cases of monomodal distribution of R-R intervals. The authors discuss Nakatsu's findings and argue that the silent zone in a Lorenz plot is a morphological expression of bimodal distribution of R-R intervals in atrial fibrillation. The silent zone may be caused by pharmacotherapy (e.g. digoxin), increased parasympathetic tension or other factors prolonging FRP. The presence of the silent zone is not a predictor of a spontaneous termination of atrial fibrillation.

Atrial Fibrillation↗
PubMed1986

Scaling in biological nuclear magnetic resonance spectral distributions.

A statistical analysis of the distribution of the eigenvalues of the chemical shift interaction as detected by nuclear magnetic resonance (NMR) spectroscopy in large biological systems is presented in the light of random matrix theory. A power law dependence is experimentally observed for the distribution of the number of eigenvalues, N, of the shielding hamiltonian with epsilon i less than or equal to E as a function of the energy E. From this cumulative distribution of energy levels, N(E), we also obtain a density of states rho(E). The exponent of the energy variation of N(E) and rho(E) are correlated with the dimensionality of the molecular system. A crossover in the values of the exponents is found in passing from low to higher energy in the spectra. Our method classifies and reduces the chemical shift data base of proteins and also demonstrates a degree of regularity in seemingly irregular spectral patterns.

Alamethicin↗