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PubMed1990

Changes in type II cell populations in monocrotaline pneumotoxicity.

Unlike many other systemically administered pneumotoxicants affecting alveolar septa, Monocrotaline (MCT) does not cause a proliferative type II cell response. To determine whether MCT has an effect that might alter the type II cell response, we determined the numerical density and volume of type II cells in lungs from MCT-treated rats. Morphometric parameters were derived from estimates of nuclear volume based on point and intercept ratios counted in electron micrographs of type II cell profiles. These were combined with point and intercept counts of alveolar septal structures and counts of nuclear profiles per unit area to calculate average cell volume and numerical density of type II cells. Areal densities of type II cell profiles were determined by light microscopic counts of alveolar parenchyma and normalized to the volume of lung parenchyma. Cell volume of type II cells was markedly increased in MCT-treated animals (1.25 X 10(3) microns3) compared with controls (3.4 X 102) microns3). Nuclear diameter of type II cells was similarly increased (8.53 microns in treated animals versus 5.81 microns in controls). The number of type II cells was markedly decreased in treated animals (1.36 X 10(6] cells per cm3 lung parenchyma compared with 7.65 X 10(6) cells per cm3 parenchyma in controls). We conclude that MCT causes marked cellular hypertrophy of type II alveolar epithelial cells and that this hypertrophy is somehow related to a failure to maintain normal cell populations in the lung of MCT-treated rats. We hypothesize that this change is analogous to the hypertrophy and mitotic inhibition that occurs in the liver of animals treated with hepatotoxic pyrrolizidine alkaloids.

Animals↗
PubMed1990

The effect of almitrine on the steady-state ventilatory response to carbon dioxide at rest and during exercise in man.

Almitrine has potential as a tool for testing the physiological role of the peripheral chemoreceptor. The effects of almitrine on CO2 chemosensitivity were studied at rest and during light exercise using a constant inflow technique that avoids the hyperoxia of rebreathing methods. The steady-state ventilatory response to CO2 was measured in two groups of six normal men before and 150 min after 100 mg oral almitrine bismesylate or placebo. One group was studied at rest, the other while pedalling at 50 W. The resting group showed a significant increase in CO2 response slope after almitrine when compared with placebo but there was no significant change in the response intercept. During exercise the individual results were very variable and after almitrine no significant change was seen in either the response slope or intercept. Control ventilation was not affected by almitrine in either group. Even in the absence of marked hyperoxia the effect of almitrine on CO2 sensitivity at rest in small. The lack of effect at 50 W is against any important role for the peripheral chemoreceptor during light exercise but other interpretations are possible.

Adult↗
PubMedDate not supplied

Comparison of postcolumn derivatization-liquid chromatography with thin-layer chromatography for determination of aflatoxins in naturally contaminated corn.

Quantitation of aflatoxins by liquid chromatography with postcolumn iodine derivatization (LC-PCD) and fluorescence detection was compared with quantitation by the AOAC CB method, 968.22. Thirty-seven naturally contaminated corn samples were ground and then divided. One portion was extracted, and the extract was cleaned up and analyzed by thin-layer chromatography according to the CB method. The second portion was extracted and cleaned up in a similar fashion, but quantitation was by the LC-PCD method. For aflatoxin B1 concentrations ranging from 0 to 150 ng/g, results obtained by the 2 methods were fitted to a linear equation with the LC-PCD results as the dependent variable. The correlation coefficient was 0.99, the intercept was near 0, and the slope was near 1. For aflatoxin B2, the correlation coefficient was 0.97, and the intercept was near 0. However, the slope of the equation relating LC-PCD concentration to TLC concentration was only 0.5. We believe that this lack of equivalence between the methods for determination of aflatoxin B2 is due to overestimation by the TLC method because the low levels present are near the TLC detection limit for B2.

Aflatoxin B1↗
PubMed1990

[Parameters for determining the time of death from post-mortem muscle contraction--precision of assessing time of death].

The objectified muscular contraction on excitation with rectangular impulses of 1 sec duration and definite current intensity is in its postmortem course characterised by: 1. Change of the shape of muscular contraction (time-course of muscular contraction) from a two peak to a one peak shape 2. postmortem decrease of the maximum force of muscular contraction on definite current intensity 3. increase of the relaxation time of muscular contraction. On an random sample of fifty bodies decrease of the maximum force and increase of the relaxation time as criteria for extrapolating the time since death were investigated. The extrapolation was performed on the basis of the regression between ln of the maximum force and time using the mean values for slope and intercept and the regression between ln of the relaxation time and the ln of the time since death respectively using the mean values for slope and intercept too. On fifty bodies the calculated 95%--limits of confidence are +/- 2.85 h (decrease of the maximum force) and +/- 2.7 h (increase of relaxation time) up to 13 hpm. The calculated 95% limits of confidence were examined on an independent random sample of 20 bodies and proved to be reliable.

Electric Stimulation↗
PubMed1979

[Postovulatory and post-implantation inhibition of fertility--general account (author's transl)].

Latest knowledge about interception and induced menstruation is discussed. Interception (postovulatory inhibition of fertility) can be undertaken by using oestrogens, anti-oestrogens and gestagens as well as non-steroid compounds. Induced menstruation is discussed as a method of post-implantation inhibition of fertility. Induction of menstruation, that is post-implantation contraception, will be feasible by means of anti-gestagens or inhibitors ov ovarian steroid biosynthesis. While most various research efforts have been undertaken, no practicable procedure has become available as yet.

Animals↗
PubMed1990

Effects of the left ventricular assist device on right ventricular function.

Right ventricular failure is a leading cause of death in patients who require the left ventricular assist device. Previous reports suggested right ventricular functional deterioration during left ventricular assist but lacked a method by which right ventricular function could be quantified adequately. This study examined the effects of left ventricular volume unloading on right ventricular systolic function by means of the stroke work/end-diastolic volume relationship, a load-insensitive index of myocardial performance. In 12 anesthetized open-chested dogs, right ventricular and left ventricular pressures were measured with micromanometers while ultrasonic dimension transducers measured left and right ventricular orthogonal diameters. Left ventricular unloading was accomplished with left atrial-to-femoral artery bypass with a centrifugal pump. Data were recorded during transient vena caval occlusion in the control state and with maximal left ventricular unloading by full support by the left ventricular assist device. Modified ellipsoidal geometry was used to calculate simultaneous biventricular volumes, and linear regression analysis of right ventricular stroke work versus end-diastolic volume was used to quantify right ventricular systolic function. Average slope and x intercept of this relationship under control conditions were 2.2 +/- 0.3 X 10(4) erg/ml and 10.7 +/- 5.0 ml, respectively. During full support by the left ventricular assist device (mean flow rate, 2.4 +/- 0.3 L/min), left ventricular end-diastolic volume decreased by 31% (p less than 0.01), left ventricular septal-free wall diameter decreased by 7% (p less than 0.001), and rate of rise of right ventricular peak positive pressure declined by 13% (p less than 0.05). The corresponding slope and x intercept of the right ventricular stroke work/end-diastolic volume relationship during full unloading of left ventricular assist device were 2.3 +/- 0.3 X 0.3 X 10(4) erg/ml and 14.3 +/- 4.8 ml, respectively; these values were not significantly different from control values (p greater than 0.5). Additionally, analysis of right ventricular end-diastolic pressure-volume relationships suggested improved right ventricular chamber compliance, although the effects were small and did not reach statistical significance (p = 0.10). These data imply that marked alterations in biventricular geometry accompanying left ventricular volume unloading by the left ventricular assist device in a normal heart do not significantly alter right ventricular performance characteristics.

Animals↗
PubMedDate not supplied

[Role of posture in the etiopathogenesis of asymmetry and flexibility of therapeutic approach].

In the orthodontic evaluation of the cranio-cervical region, the relation between the form and the function is very important, specially if we consider the most frequent component of the modification of the armony of the system, the asymmetries, that we can classify as skeletal, functional and mixed. In this regards, the cervico-cranio-mandibular posture is a very important factor very often associated with the proper function of the respiratory system. The different factors, as cervical, nasal, temporo-mandibular and dento-alveolar are considered. On this basic approach, a diagnostic procedure is presented, in order to obtain a complete evaluation of the patient by considering the dental and skeletal age, the amount of compensation, the presence of the signs and symptoms of the dysfunction. We obtain a therapeutic procedure that must be individualized: the most important times of the treatment are the interceptive approach, followed by the orthodontics steps and finally, the reevaluation of the results. The guide line of these steps are mostly a continuous monitoring of the symptoms, the priority of the sequences of the treatment, the use of a repositioning splint and a selective biomechanics. Four cases are presented at different ages, with asymmetries, on which the posture play an important role. The treatment procedures and the satisfactory results show the possibility of an interceptive approach of the asymmetries, at least of the postural component in the adult patient, and the important role of the orthodontist in the treatment of these malocclusions.

Adolescent↗
PubMed1979

Incorrect least-squares regression coefficients in method-comparison analysis.

The least-squares method is frequently used to calculate the slope and intercept of the best line through a set of data points. However, least-squares regression slopes and intercepts may be incorrect if the underlying assumptions of the least-squares model are not met. Two factors in particular that may result in incorrect least-squares regression coefficients are: (a) imprecision in the measurement of the independent (x-axis) variable and (b) inclusion of outliers in the data analysis. We compared the methods of Deming, Mandel, and Bartlett in estimating the known slope of a regression line when the independent variable is measured with imprecision, and found the method of Deming to be the most useful. Significant error in the least-squares slope estimation occurs when the ratio of the standard deviation of measurement of a single x value to the standard deviation of the x-data set exceeds 0.2. Errors in the least-squares coefficients attributable to outliers can be avoided by eliminating data points whose vertical distance from the regression line exceed four times the standard error the estimate.

Blood Chemical Analysis↗
PubMed1989

Individual variability in symptoms, ischemic threshold and cardiovascular efficiency during exercise testing in patients with effort angina.

This study assessed both group and individual variability of ECG exercise stress test in patients with effort angina. Forty-five untreated patients with typical effort angina, without evidence of spontaneous angina, with a positive exercise stress test (ST depression greater than 0.2 mV) and angiographically documented coronary artery disease were studied. Four multistage exercise stress tests were performed, two in the morning and two in the afternoon, on two consecutive days. Forty-four patients completed the protocol for a total of 176 exercise stress tests. For each exercise stress test the following parameters were analyzed: time to 0.15 mV ST segment depression (time to ischemia); rate-pressure product at ischemia (ischemic threshold); slope and intercept of the linear regression between rate-pressure product and time of exercise. Silent effort ischemia was largely prevalent: 21 patients (48%) experienced chest pain in all four tests, but only seven showed a consistent time relationship between pain and ECG changes. Symptomatic patients did not appear different from the asymptomatic ones in terms of clinical and angiographic data. When group data were analyzed for each parameter the four exercise stress tests appeared reproducible. In contrast, when individual variability of each parameter was computed as the percentage difference between range (maximum--minimum) and maximal value obtained in the series of four exercise stress tests, a large variability was detected. Variability of time to ischemia, was 27.2 +/- 17.4%. This resulted from a random combination of variability in ischemic threshold (19.1 +/- 9.2%), slope (28.4 +/- 12.8%) and intercept (22.7 +/- 10%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Experimental study in the cat on the alveolar density and heterogeneity in the obstructed lung. Comparison with the emphysematous lung in the aged].

An experimental model of lung obstruction has been achieved in the cat reared in our laboratory. 30 young adults (J) and one adult subject (A) had tracheal stenosis from 8 to 15 weeks and were the object of a study of pulmonary airways and were compared with four young controls and seven older controls. The presence of emphysema was revealed by microscopy. The size of the alveoli was measured by the mean linear intercept (MLI). The study was systematized by an image analyser giving the ratio of airway spaces to pulmonary tissue (% of surface). The mean value S represented the alveolar section in the lung. Alveolar heterogeneity was expressed by the dispersion of the point values S around the mean S. The animals had episodes of ventilatory distress. Cytology of the broncho-alveolar lavage performed when the animals were sacrificed did not distinguish between the obstructive and other subjects. Emphysema was found in 10 out of 22 of the young stenosed animals. No control J were abnormal. 5 adults were emphysematous through ageing (5 years or more). The mean linear intercept of the alveoli was increased in the emphysematous (115%) and even more in the obstructive cases without or with emphysema where MIL attained 173%. The obstructive lung, whether emphysematous or not, is heterogeneous. Emphysema, always focal, corresponded to an alveolar section which was weakened (S less than S controls - 2 standard deviations) for 40% of the older subjects and for 50% of the J obstruction, up to two times more often than in obstruction without emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

Critical collateral bloodflow level for salvage of ischemic myocardium.

Twenty-three dogs with occluded coronary arteries were retrospectively analyzed in an attempt to estimate the critical collateral bloodflow for salvaging ischemic myocardium. Under pentobarbital anesthesia a coronary branch was occluded by an embolus. The field of the occluded artery (ischemic zone) was determined by subsequent autoradiography of 141cerium (141Ce) labelled microspheres injected into the left ventricle, 2 to 8 mins after embolization. The regional myocardial bloodflow was also measured by microspheres. Dogs were sacrificed after 24 h (n = 9) or 48 h (n = 14) of coronary occlusion and the data pooled. Size of the necrotic myocardium, determined by tetrazolium staining, was expressed as a percentage of the ischemic zone (percentage necrosis). Percentage necrosis (%N) was negatively correlated with the collateral flow as a percentage of the flow of the corresponding nonischemic layer (%CF) whether the subendocardial, midmyocardial or subepicardial collateral flow was considered. For subendocardium, %N = 81.15 - 3.96%CF and r = -0.77; for midmyocardium, %N = 80.60 - 1.98%CF and r = -0.71; and for subepicardium, %N = 90.23 - 1.03%CF and r = -0.90, all P less than 0.01. Because there is a transmural gradient of the collateral flow in the ischemic zone, the zero necrosis intercept of the regression line of percentage necrosis-subendocardial percentage collateral flow plot would represent the minimal flow level for myocardial survival. This intercept was calculated to be 20.5% normal with a 95% confidence interval between 10.4% and 37.5% (df = 21).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Multilayer fluorescent immunoassay technique.

We describe a new multilayer immunoassay element for the determination of haptens in undiluted serum and plasma. Polysaccharide layers are coated onto a plastic base. The signal layer contains an immobilized antibody and a fluorescent-labeled hapten. A second layer, containing a pigment, acts as an optical screen. Sample spreading is achieved by a molded grid in contact with the upper layer of the immunoassay element. After sample is added to the element, endogenous analyte competes with the labeled hapten for the binding sites of the immobilized antibody; equilibrium is reached in 4-12 min. Because of the relative liquid-holding capacities of the layers and the grid, only a small amount of the free components remains in the signal layer. The signal is measured by front-surface fluorimetry. This technology has been applied to theophylline and thyroxin assays. Within- and between-run CVs range from 3% to 6%. Comparisons with fluorescent polarization immunoassays (Abbott TDx) showed excellent correlation (theophylline: r = 0.98, slope = 1.07, intercept = 0.3; thyroxin: r = 0.97, slope = 0.91, intercept = 0.8). The new method requires only one pipetting step (sample delivery) and is potentially applicable to a wide range of analytes.

Fluorescence Polarization↗
PubMed1989

[Evaluation of the contractile state of the left ventricle before and after aortic valve replacement from end-systolic stress-volume relations in patients with chronic aortic regurgitation].

Before and one month after aortic valve replacement, the contractile state of the left ventricles in 10 patients with chronic aortic regurgitation were studied. The slope and intercept of the end-systolic stress-volume relationship (ESSVR) determined by M-mode echocardiography during intravenous infusion of Nitroprusside were used as an index of myocardial contractility. We found that the end-systolic wall stress-volume relationship from more than four points of pressure and dimension data have shown the linear relation for each subject with linear coefficients ranging from 0.848-0.997. There was no significant change in the slope of ESSVR between the pre- and early postoperative studies (1.66 +/- 0.37 to 1.92 +/- 1.02; p greater than 0.05), however, the intercept decreased significantly (44.7 +/- 32.4 to 29.4 +/- 28.0; p less than 0.01), which meant the leftward shift of the line of ESSVR and may imply the improvement of myocardial contractility. On the contrary, the fractional shortening decreased significantly (25.6 +/- 8.5 to 18.9 +/- 8.8%; p less than 0.01), reflecting marked reduction in preload or left ventricular end-diastolic volume (7.52 +/- 1.07 to 6.04 +/- 1.38; p less than 0.01). The change in the slope of the liner of ESSVR demonstrated that myocardial contractility might not be depressed at this time but rather improving.

Adult↗
PubMed1989

Stereological studies on rat spinal neurons during postnatal development: estimates of mean perikaryal and nuclear volumes free from assumptions about shape.

A stereological method for estimating the mean volumes of particles independent of assumptions about their shapes is illustrated using neurons in the ventral horn of rat cervical spinal cord. Male rats of 20 and 120 days post partum age were killed by intracardiac perfusion with formaldehyde/glutaraldehyde solutions. Cervical enlargements were removed, trimmed and embedded in resin. Randomised sections of ventral horn were photographed in a systematic pattern and used to estimate the volume-weighted mean volumes of neuronal perikarya and their nuclei. Volumes were estimated from point-sampled intercepts using rulers to classify intercept lengths. Classifying motoneuron perikarya was extremely reproducible, group means (coefficients of variation) at 120 days post partum being 25,190 microns3 (23%) and 24,250 microns3 (25%) in two separate trials. Classifying all neurons at the same age gave values of 20,520 microns3 (22%) and 22,490 microns3 (28%) in two trials. The mean perikaryal volumes of motoneurons at 20 and 120 days of age were not significantly different but nuclear volumes increased from 1,580 microns3 (16%) at 20 days to 2,660 microns3 (28%) at 120 days. These results illustrate the value of the method for obtaining unbiased and efficient estimates of the sizes of irregular perikarya and their nuclei. The benefit is that sizes can be estimated without biases due to simplifying assumptions about perikaryal/nuclear shape or nucleolar location. The influence of section thickness (even of thick paraffin sections) on the estimates is also negligible.

Animals↗
PubMed1988

Enzymic determination of the free cholesterol fraction of high-density lipoprotein in plasma with use of 2,4,6-tribromo-3-hydroxybenzoic acid.

A highly sensitive enzymic colorimetric reagent is described for determination of the free cholesterol fraction of high-density lipoprotein (HDL), which represents about 20% of the total cholesterol content of this lipoprotein. For greater sensitivity with respect to cholesterol, I used 2,4,6-tribromo-3-hydroxybenzoic acid instead of phenol in the cholesterol oxidase/peroxidase/4-aminoantipyrine reagent system. This allows determination of the free cholesterol fraction of HDL isolates prepared with polyethylene glycol 6000, a method for precipitating beta-lipoprotein that involves a twofold dilution of plasma. The reagent, adapted for use with a Cobas-Bio centrifugal analyzer, results in between-run and within-run CVs of less than 3% and a linearity to at least 400 mg of HDL free cholesterol per liter. Comparison with results by Trinder's cholesterol method, which measures cholest-4-en-3-one at 232 nm, showed good correlation (r = 0.9829, slope 1.0001, and y-intercept +2.4797 mg/L). With the manual procedure for HDL free cholesterol, between-batch and within-batch CVs were less than 5%, and results correlated well with those by the automated method (r = 0.9975, slope 0.9839, and y-intercept +2.4327 mg/L). The mean (and SD) HDL free cholesterol for 123 men was 96.8 (30.6) mg/L and for 122 women 136.4 (36.8) mg/L, indicating a distinct sex-related difference, similar to that found for HDL total cholesterol. HDL free cholesterol in plasma may therefore be a potential new predictor of coronary heart disease.

Adult↗
PubMed1988

An enzyme immunoassay compared with a ligand-binding assay for measuring progesterone receptors in cytosols from breast cancers.

To assay progesterone receptor (PR), we compared Abbott's enzyme immunoassay (PR-EIA) with a ligand-binding assay involving dextran-coated charcoal (PR-DCC), using cytosols prepared from 109 breast-cancer biopsies. Results by the two PR methods agreed well. Least-squares analysis produced a line of best fit having a slope of 0.88, an intercept on the PR-EIA axis of 16 fmol per milligram of protein, and a correlation coefficient (r2) of 0.87. To evaluate whether accurate PR-EIA measurements could be obtained on stored cytosols, we compared PR-EIA values for fresh cytosols with values for cytosols stored for various lengths of time up to 13 weeks. Agreement was excellent, especially when the samples showing very high binding (greater than 600 fmol per milligram of protein) were excluded. The lines of best fit after least-squares analyses of the remaining values had slopes between 1.0 and 1.1, intercepts less than 3 fmol/mg, and r2 all greater than 0.91.

Adult↗
PubMed1988

A kinetic analysis of electron transport across chromaffin vesicle membranes.

Some types of secretory vesicles, such as the chromaffin vesicles of the adrenal medulla, have cytochrome b561 which is believed to mediate the transfer of electrons across the vesicle membrane. To characterize the kinetics of this process, we have examined the rate of electron transfer from ascorbate trapped within chromaffin vesicle ghosts to external ferricyanide. The rate of ferricyanide reduction saturates at high ferricyanide concentrations. The reciprocal of the rate is linearly related to the reciprocal of the ferricyanide concentration. The internal ascorbate concentration affects the y intercept of this double-reciprocal plot but not the slope. These observations and theoretical considerations indicate that the slope is associated with a rate constant k1 for the oxidation of cytochrome b561 by ferricyanide. The intercept is associated with a rate constant k0 for the reduction of cytochrome b561 by internal ascorbate. From k0 and standard reduction potentials, the rate constant k-0 for the reduction of internal semidehydroascorbate by cytochrome b561 can be calculated. Under conditions prevailing in vivo, this rate of semidehydroascorbate reduction appears to be much faster than the expected rate of semidehydroascorbate disproportionation. This supports the hypothesis that cytochrome b561 functions in vivo to reduce intravesicular semidehydroascorbate thereby maintaining intravesicular ascorbic acid.

Adrenal Medulla↗
PubMed1988

Restoration of left ventricular systolic performance after reattachment of the mitral chordae tendineae. The importance of valvular-ventricular interaction.

Clinical studies suggest that chorda-sparing mitral valve replacement techniques are associated with superior postoperative outcome, and several animal experiments have shown that disruption of the mitral subvalvular apparatus is followed by deterioration of left ventricular systolic function. One essential element, however, underlying the importance of chordal integrity for left ventricular function remains unproved: All investigators heretofore have been unable to demonstrate that left ventricular systolic performance can be restored by chordal reattachment after disruption of annular-papillary continuity. Therefore, we studied the effects of chordal detachment and subsequent chordal reattachment on left ventricular systolic performance using an in situ, isovolumic heart preparation in 10 halothane-anesthetized swine. The slope and left ventricular volume intercept of the isovolumic peak pressure-volume relationship were measured to assess global left ventricular systolic performance independent of load. Coronary perfusion pressure was maintained constant (95 +/- 6 mm Hg [+/- standard deviation]), and heart rates were in the physiologic range (133 +/- 26 min-1). Slope changed significantly (repeated measures analysis of variance, p = 0.0002), decreasing by 29% (from 4.74 +/- 0.94 to 3.37 +/- 0.87 mm Hg/ml, p less than 0.001) after chordal detachment and then returning to baseline (6.05 +/- 2.38 mm Hg/ml, p = 0.001) after chordal reattachment. Slope after chordal reattachment was not significantly different from the baseline value (p = 0.074). Volume intercept did not change significantly (p = 0.44) at any time. We conclude that the acute decrease in left ventricular contractility associated with surgical interruption of annular-ventricular continuity can, in fact, be reversed by chordal reattachment in this experimental model (isovolumically contracting normal porcine hearts). These data provide concrete confirmation of the concept of valvular-ventricular interaction; if these findings can be corroborated in the dilated, human left ventricle, such would strongly support efforts to preserve the mitral chordae tendineae during clinical mitral valve replacement to optimize postoperative left ventricular function.

Animals↗