Values Of Vc Research Articles

Estudio de la difusión pulmonar de monóxido de carbono en enfermos con estenosis mitral

Objective: The aim of our work has been the study of CO diffusion capacity in mitral valve stenosis patients. Method: We have studied 15 control subjects and 15 patients with mitral valve stenosis. We performed spirometry study and CO pulmonary diffusion tests (DLCO) by single breath method to determine two compo nents: pulmonary capillary blood volume (Vc) and membrane diffusion factor (Dm). In addition, in mitral valve stenosis patients we performed a ecocardiography-doppler study. Results: The mitral valve stenosis group had higher values of DLCO and Vc and a lower ratio of Dm/Vc than the control group. There is a negative correlation between Vc and the mitral valve area (r = -0.63; p = 0.037). We do not find any another correlation between the rest of ecocardiography doppler parameters and lung function test variables that we have measured. We have not found any differences between both groups in Dm. Conclusions: Mitral valve stenosis patients present a increase of CO pulmonary diffusion capacity and pulmonary capillary blood volume without changes in membrane diffusion factor.

NbN/Nb/AlOx/Nb/NbN junctions fabricated using an ultra-highvacuum dc-magnetron sputtering system

This paper presents the electrical characteristics of NbN/Nb/AlOx/(Nb)/NbN junctionsfabricated using an ultra-high vacuum (UHV) dc-magnetron sputtering system. TheNbN/Nb/AlOx/(Nb)/NbN junctions show overdamped characteristics at or over 10 K, although theyshow small- or medium-hysteretic characteristics at 4.2 K. The UHV sputtering system with aload-lock chamber enables us to prepare high-quality NbN films with high reproducibility and verythin Al2O3 films with high homogeneity. We have obtained the overdamped junctions with thecritical current density Jc up to 10 kA cm-2 and the characteristic voltage Vc up to 0.50 mV over10 K. When Al oxidation conditions were changed, Jc and Vc were obtained in the range of 0.63-10 kA cm-2and 0.22-0.44 mV, respectively. These Jc and Vc values were much larger than those, typicalvalues of 1.1 kA cm-2 and 0.20 mV, of junctions fabricated using a conventional batch-type sputteringsystem. When the upper-Nb film thickness was changed, Jc and the degree of hysteresis, Ir/Ic, wereobtained in the range of 0.31-0.64 kA cm-2 and 0.87-1.0, respectively. The spread of Ic at 10 K was astandard deviation, 1σ, of 6.3% for a series array of 1000 junctions and 4.4% for 100 junctions.

Free‐volume variation in polyethylenes of different crystallinities: Positron lifetime, density, and X‐ray studies

AbstractHigh‐quality positron lifetime measurements (70 million total counts) are reported for polyethylenes (PEs) of different crystallinities (Xc = 3–82%). The specific volumes of the crystalline and amorphous phases (Vc and Va, respectively) were estimated from density and wide‐angle X‐ray scattering (WAXS) experiments. Some samples (those with low values of Xc) were branched PEs, and those with high values of Xc were linear PEs for which Xc was varied with changes in the crystallization temperature. Both Vc and Va increase with decreasing Xc in the range 0% ≤ Xc ≤ 56% (the branched PEs) but are constant for Xc ≥ 56% (the linear PEs). The lifetime spectra were analyzed with the MELT and LIFSPECFIT routines. Artifacts that can appear in the spectrum analysis were checked via an analysis of computer‐generated spectra. Four lifetime components appeared in all of the PEs; the two long‐lived ones are attributed to pick‐off annihilation of ortho‐positronium (o‐Ps) in crystalline regions (τ3) and in holes of the amorphous phase (τ4). With increasing Xc, τ3 decreases from about 1.2 to 1 ns, τ4 decreases from 3.0 to 2.5 ns, and the intensity I4 decreases from 29 to 0%. An increase in I3 from 6 to 12% was observed. A comparison with simulations shows that the true I3 value approaches 0 for Xc → 0%. The decrease in I4 is weaker than the increase in Xc; this leads to the conclusion that the apparent specific o‐Ps yield in the amorphous phase I4Xc increases with Xc. Possible reasons for this surprising results are discussed. The fractional free hole volume [h = (Va − Vocc)/Va, where Vocc is the crystalline occupied volume] was estimated from density and WAXS results. Between Xc = 0 and 56%, h decreases from 0.151 to 0.090, but it does not change further above Xc = 56%. The mean size (v) of the local free volumes (holes) estimated from τ4 decreases from 200 to 150 Å3. The number density of holes (Nh) calculated from these values (Nh = h/v) also decreases from 0.8 to 0.6 nm−3 in the range 0% ≤ Xc ≤ 56%. The values of Va, Vc, h, and Nh increase with an increasing degree of branching but do not vary for linear PEs. The possible influence of a crystalline–amorphous interfacial phase (three‐phase model) on the observed lifetime parameters is also discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 65–81, 2002

Volumetric determination of progression in autosomal dominant polycystic kidney disease by computed tomography

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive renal enlargement and renal failure. We evaluated sequential radiocontrast-enhanced computed tomography (CT) scans to determine the rate of kidney enlargement in patients with ADPKD. Ten adult patients with ADPKD (4 men and 6 women) with initial serum creatinine levels </=1.6 mg/dL had at least two sequential CT scans more than three years apart. The mean patient age at the initial CT study was 33.8 years, and the mean initial serum creatinine concentration was 1.1 mg/dL (range 0.6 to 1.6 mg/dL; range of calculated creatinine clearances 60 to 135 mL/min/1. 73 m2). Total volume (Vt) was determined by manual tracing of renal areas in contiguous 5 to 10 mm thick axial CT slices for each kidney. The area of noncystic parenchyma (Vp) in each slice was determined by differential densitometry segmentation analysis of contrast-enhanced tissue, and total cyst volume (Vc) was the difference between Vt and Vp. The mean diameters of individual cysts were measured sequentially in selected cases. The mean initial Vt, Vp, and Vc values (+/- SEM) were 561 +/- 66, 243 +/- 19, and 317 +/- 57 mL per kidney, respectively. In 10 patients, after a mean of 5.7 years (range 3.3 to 11.9), Vt increased 323 +/- 79 mL (P < 0.01, range -25 to 1182 mL); the rate of volume increase was 53.9 +/- 10.4 mL/year/kidney (P < 0.001). In eight patients with repeat contrast-enhanced scans, Vt, Vp, and Vc increased 211 +/- 58 mL (P < 0.005), 26 +/- 11 mL (P > 0.05), and 185 +/- 52 mL (P < 0.01), respectively. In 19 individual spherical cysts selected in six patients, the mean initial volume was 15.0 +/- 7.2 mL (range 1.1 to 137 mL), and the average rate of volume increase was 0.52 +/- 0.21 mL/month (P < 0.025, range 0.02 to 4.15 mL/month). In five patients who eventually required dialysis, 11.2 years after the initial CT scan, the initial cyst/kidney volume ratio (combined for both kidneys) exceeded 0.43; four patients with lower cyst/kidney volume ratios had serum creatinine levels <1.5 mg/dL, 8.7 years after the initial CT scan. On the basis of this preliminary survey of archival material, we conclude that conventional contrast-enhanced CT scans can be used to quantitate volume components of progression in ADPKD. The rates of individual kidney and cyst enlargement are highly variable within and between patients, but overall, the values increase over time. The volume fraction of kidneys comprised of cysts may be a useful indicator of ADPKD progression.

A mechanistic evaluation of photosynthetic acclimation at elevated CO2

SummaryPlants grown at elevated pCO2 often fail to sustain the initial stimulation of net CO2 uptake rate (A). This reduced, acclimated, stimulation of A often occurs concomitantly with a reduction in the maximum carboxylation velocity (Vc,max) of Rubisco. To investigate this relationship we used the Farquhar model of C3 photosynthesis to predict the minimum Vc,max capable of supporting the acclimated stimulation in A observed at elevated pCO2. For a wide range of species grown at elevated pCO2 under contrasting conditions we found a strong correlation between observed and predicted values of Vc,max. This exercise mechanistically and quantitatively demonstrated that the observed acclimated stimulation of A and the simultaneous decrease in Vc,max observed at elevated pCO2 is mechanistically consistent. With the exception of plants grown at a high elevated pCO2 (&gt; 90 Pa), which show evidence of an excess investment in Rubisco, the failure to maintain the initial stimulation of A is almost entirely attributable to the decrease in Vc,max and investment in Rubisco is coupled to requirements.

Diffusion capacity and haemodynamics in primary and chronic thromboembolic pulmonary hypertension

The transfer factor of the lung for carbon monoxide (TL,CO) is decreased in patients with pulmonary hypertension. The pulmonary membrane diffusion capacity (Dm) and pulmonary capillary blood volume (Vc), were studied to establish: 1) the relative contribution of the components of the transfer factor to the decrease in TL,CO; 2) whether differences exist between primary pulmonary hypertension (PPH) and chronic thromboembolic pulmonary hypertension (CTEPH); and 3) the relationship between these parameters and haemodynamic parameters. Dm and Vc were determined in 19 patients with PPH and in eight patients with CTEPH. The patients had been referred for consideration for lung transplantation. Haemodynamic parameters were assessed by heart catheterization. In the PPH group, Vc was reduced in 12 of 19 patients (mean+/-SD Vc 72+/-14% of the predicted value) and Dm in 17 of 19 patients (60+/-22% pred). In the CTEPH group, Vc was reduced in six of eight patients and Dm in seven of eight patients. The mean TL,CO Dm and Vc values were similar to those in the PPH group. The reduction in pulmonary membrane diffusion capacity was significantly greater than that in pulmonary capillary blood volume. No differences in pulmonary and cardiovascular functional values were found between the groups. Right atrial pressure showed a significant negative correlation with pulmonary capillary blood volume and an increased pulmonary vascular resistance was associated with a decrease in pulmonary membrane diffusion capacity. These results suggest pronounced functional impairment of the alveolocapillary membrane in these patients.

Percolation Behavior of Conductor-Insulator Composites with Varying Aspect Ratio of Conductive Fiber

The electrical properties of composite electroceramics are determined by the concentration, shape and distribution of filler phase in matrix. The carbon fiber-filled polymer was chosen as a model system and the electrical conductivity was measured as a function of carbon fiber content and the aspect ratio (AR) of the fibers to understand the percolation behavior of the composites. The composites of carbon fiber (1∼9 vol.%) and thermoplastic polymer were fabricated in a mold press with the aspect ratio of carbon fiber varying between 4 and 10. The percolation threshold volume concentrations (V c) of transition from the insulator to the conductor decreased as the fiber aspect ratio increased. With the fibers segregated at the polymer-polymer interfaces in the present study, V c values were much smaller than those with the fibers randomly distributed in the matrix shown in other studies. The inverse relation between V c and AR was found as expected. From the comparison with other experimental and simulated data, we concluded that the slope in 1/V c versus AR plot is a strong function of fiber segregation.

Dose-dependence and repeated-dose studies for receptor/gene-mediated pharmacodynamics of methylprednisolone on glucocorticoid receptor down-regulation and tyrosine aminotransferase induction in rat liver.

Dose-dependent and repeated-dose effects of methylprednisolone (MPL) on down-regulation of glucocorticoid receptor messenger RNA (GR mRNA) and GR density, as well as tyrosine aminotransferase (TAT) mRNA and TAT induction by receptor/gene-mediated mechanisms in rat liver were examined. A previously developed pharmacokinetic/pharmacodynamic (PK/PD) model was used to design these studies which sought to challenge the model. Three groups of male adrenalectomized Wistar rats received MPL by i.v. injection: low-dose (10 mg/kg at Time 0), high-dose (50 mg/kg at Time 0), and dual-dose (50 mg/kg at Time 0 and 24 hr). Plasma concentrations of MPL, and hepatic content of free GR, GR mRNA, TAT mRNA, and TAT activity were determined. The P-Pharm program was applied for population analysis of MPL PK revealing low interindividual variation in CL and Vc values (3-14%). Two indirect response models were applied to test two competing hypotheses for GR mRNA dynamics. Indirect Pharmacodynamic Response Model I (Model A) where the complex in the nucleus decreases the transcription rate of GR mRNA better described GR mRNA/GR down-regulation. Levels of TAT mRNA began to increase at 1-2 hr, reached a maximum at 5-6 hr, and declined to the baseline at 12-14 hr after MPL dosing. The induction of TAT activity followed a similar pattern with a delay of about 1-2 hr. The low-dose group had 50-60% of the TAT mRNA and TAT induction compared to the high-dose group. Since the GR density returned to about 70% of the baseline level before the second 50 mg/kg dose at 24 hr, tolerance was found for TAT mRNA/TAT induction where only 50-60% of the initial responses were produced. Our fourth-generation model describes the dose dependence and tolerance effects of TAT mRNA/TAT induction by MPL involving multiple-step signal transduction controlled by the steroid regimen, free GR density, and GR occupancy. This model may provide the foundation for studying other induced proteins or enzymes mediated by the similar receptor/nuclear events.

The role of hybridization on valence transitions in the spinless Falicov-Kimball model

The spinless Falicov-Kimball model with hybridization is studied in one dimension using small-cluster exact-diagonalization calculations. The resultant exact solutions are used to examine the f-state occupation nf as a function of f-level energy Ef, hybridization V and d-f interaction U. In addition, the phase diagram based on the finite-size scaling analysis of the single particle excitation energy is discussed both for the symmetric (Ef = 0) and unsymmetric (Ef ≠ 0) case. A number of remarkable results are found. (i) The f-electron occupation number as a function of Ef changes continuously, confirming renormalization-group results. No discontinuous transitions are observed at finite V. (ii) In the symmetric case the insulating state persists as the ground state for all nonzero V. (iii) Outside the symmetric point the hybridization stabilizes the metallic state for lower V and the insulating state for higher V. (iv) The metal-insulator transition takes place at V = Vc > 0. The values of the critical hybridization strength Vc are of order 10−2.

Does parallel conductance vary during systole in the human right ventricle?

Right ventricular (RV) contractile performance remains poorly characterised, particularly in humans. Conductance catheter techniques have the potential to overcome the geometric difficulties in RV volume measurement that have hindered systematic studies of RV pressure volume relations. The present study examines changes in parallel conductance (Vc) that may occur during the cardiac cycle in the human right ventricle. Using signals obtained from custom-built conductance catheters, six isochronal systolic values of Vc (Vc(t)) were measured during hypertonic saline wash-in. Studies were performed in nine patients undergoing right heart catheterisation. Their ages ranged from 7 to 39 years (median = 16) and their weights ranged from 20.3 to 84.7 kg (median = 50.0 kg). Measurements of mean Vc and isochronal Vc(t) and its variability during systole were assessed. Mean Vc was measured using the Baan technique (Vc(Baan)), Vc(t) was measured from six systolic isochrones obtained during the same period of hypertonic saline wash-in. The temporal changes in Vc(t) were small (mean 5.8%, median = 4.4%, range = 0.6-17.9%) of total corrected end-diastolic volume (mean maximal variation of 7.7 ml). The value of Vc(t) obtained at dp/dtmax (mean = 99.1 ml; median = 104.75 ml; range 20.15-196.7 ml) was not significantly different to that obtained at dp/dtmin (mean = 100.0 ml; median = 110.87 ml; range = 20.0-204.2 ml) (P > 0.05), but both were higher than the single Vc measurement (Vc(Baan)) obtained using the standard approach (P = 0.02). The correlation between Vc(Baan) and Vc(t) for group data; (Vc(Baan) = 89.69 ml, s.d. = 43.73 ml; Vc(t) = 98.16 ml, s.d. = 50.16 ml) produces a regression slope of 0.99 for all studies (P = 0.02). We conclude that parallel conductance does vary during systole in the human right ventricle of adults and older children after repair of congenital abnormalities but there is no significant difference in Vc(t) at dp/dtmin and dp/dtmax. However, there was a significant difference when the isochronal Vc(t) measurement is compared with the standard single value technique (Vc(Baan)) obtained using the hypertonic saline wash-in method. The excellent correlation between Vc(t) and Vc(Baan) suggests that the correction of Vc for the phase of the cardiac cycle is unnecessary for most purposes when studying the human right ventricle.

人工土壌の植生限界と流失限界 斜面緑化用人工土壌の開発（第２報）

In this study non-erosive soil materials have been developed in order to realize a green slope in opencut mining. Practically, the vegetation limit and the erosion limit of artificial soil were determined on the basis of the vegetation tests of lawn grass and the erosion tests by water jet respectively.The specimens of soil were made of the tailings of cyanide leaching at the Kushikino gold mine through the following two processes;(1) a mixture of the tailings, water, portland cement and woody fi ber was crushed under 12 mesh after the primary generation of cohesive strength for a specific time, (2) the crushed products were applied to the tests of the secondary generation of cohesive strength after charging in a pot and consolidating under various compressive stress.From the results of the above tests it was proved that the cohesive strength R{τ, ρ, η} of the soil could coexist within the range between the vegetation limit Vc and the erosion limit Ec as given by the following inequality.Vc >R{τ, ρ, η} >EcHere, the time τ of the primary generation of cohesive strength, the consolidating stress ρ and the fiber content η are the parameters of the soil strength. The measured values of Vc and Ec were 140 and 60 kg f/cm2 respectively.

Molecular modelling of polymers, 1. Prediction of critical values of oligomethylenes

AbstractMost procedures for the estimation of critical values of oligomethylenes assume these critical values to depend only on the chain length n and/or the molecular weight M. In this work, we introduce new equations for estimating the critical values by inclusion of quantum chemical data calculated by a semiempirical SCF‐MOSCF‐MO: Self‐consistent field, molecular orbital. method (AM1). These models give a much superior prediction for the critical values such as the normal boiling point Tb, critical temperature Tc, critical pressure Pc, critical valume Vc, surface tension yb and enthalpy of vaporization ΔHvp of 18 oligomethylenes. The predictions for polyethylene (with infinite chain length) for the values of Tb, Tc, Pc, Vc, ΔHvp and yb are 1029.3 K, 1029.3 K, 1.013 bar, 15723.3 m3/mol, 0 KJ/mol and 0 mN/m, respectively.

Kinetic and Spectroscopic Studies on Acyl Radicals in Solution by Time-Resolved Infrared Spectroscopy

A number of acyl radicals, RĊ=O, have been generated in hexane or di -t-butyl peroxide as solvent at room temperature by 308 nm laser flash photolysis, and their spectroscopic and kinetic properties have been examined by time-resolved infrared spectroscopy. The C=O stretching frequencies for the RĊ=O radicals are found to be higher than those of the corresponding aldehydes, RCHO, by between 108 and 128 cm-1, an effect attributed to a higher C=O bond order in the radicals. For the RĊ=O radicals some typical values of vC =O are: CH3Ċ=O, 1864 cm-1; (CH3)3CĊ=O, 1848 cm-1; and C6H5Ċ=O, 1828 cm-1, while the corresponding acylperoxyl radicals, RC(O)OO, formed by reaction with oxygen have vC =O values of 1838, 1840 and 1820 cm-1, respectively. The acyl radicals exhibit a reactivity towards a variety of substrates that is roughly comparable to that of simple alkyl radicals. For reactions of the benzoyl radical some typical rate constants/M-1 s-1 are: CCl4, 6.0x104; C6H5SH, 4.8×107; CCl3Br, 2.2×108; Tempo, 1.1×109; and oxygen, 1.8×109. Alkanoyl radicals have a rather similar reactivity to benzoyl. The propanoyl radical reacts with tributyltin deuteride with a rate constant of 3×105 M-1s-1. The hex-5-enoyl radical undergoes a 5-exo-trig cyclization to form the 2-oxocyclopentylmethyl radical with a rate constant of 2.2×105 s-1, a value which is almost identical to that for cyclization of the hex-5-enyl radical. It is hoped that our kinetic data will prove useful in the planning of organic synthetic strategies which involve acyl radical chemistry.

Pharmacokinetics and Pharmacodynamics of Pentazocine in Children

Pharmacokinetics and ventilatory effects of a single intravenous dose of 0.5 mg/kg of pentazocine were studied in ten children aged 4 to 8 years after ophthalmic surgery. Elimination half-life (mean +/- S.D.) was 3.0 +/- 1.5 hr and clearance 21.8 +/- 5.9 ml/min./kg. The values for Vc, Vss and V beta were 0.73 +/- 0.21, 4.0 +/- 1.2 and 5.3 +/- 2.1 l/kg, respectively. The pharmacokinetic parameters were similar to those of adults. After administration of pentazocine decrease in ventilatory rate and oxygen saturation and increase in end-tidal carbon dioxide were relatively fast and steep. Oxygen saturation of four patients decreased below 90% and in one patient the decrease did not recover instantly and additional oxygen was given for 2 min. No patient needed assisted ventilation. Only clinically insignificant changes in heart rate and mean arterial pressure were observed. The duration of analgesia was 164 +/- 59 min. No serious side-effects appeared.

Arterial and venous blood samplings in pharmacokinetic studies: vancomycin in rabbits.

The pharmacokinetics of vancomycin were evaluated simultaneously using both arterial and venous plasma data in five rabbits after a rapid bolus intravenous (i.v.) dosing. Initial arterial to venous concentration ratios at 5 s after i.v. injection were the highest, with values of 27.1, 36.2, 36.6, 43.7 and 29.7 for rabbits 1-5, respectively. This could be the result of diffusion of vancomycin from the arterial plasma into the extravascular tissues. Both curves decayed in parallel at the terminal phase with the venous levels higher than the arterial levels by 23, 37, 34, 13 and 14% for rabbits 1-5, respectively. This difference could be the result of continuous release of vancomycin from the extravascular tissues to the venous blood. Detailed analysis showed differences in various pharmacokinetic parameters based on arterial and venous data. For example, values for venous Vc were 9.2, 11, 1.9, 7.2 and 8.8 times greater than the arterial values for rabbits 1-5, respectively. The values for both venous Vss and MRT were higher than those of the arterial values in all five rabbits studied. This could be due to more extensive distribution of vancomycin in the extravascular tissues. A plot of 1/Q (urine flow rate) versus 1/ClR of vancomycin yielded a straight line in rabbits 6-10, indicating that the renal clearance of vancomycin in rabbits is dependent upon urine flow.

Membrane diffusion of the lungs in patients with chronic renal failure

Patients with chronic renal failure (CRF) and haemodialysis treatment usually have a reduced CO transfer factor. The aim of this study was to evaluate the effects of alveolar wall fibrosis and of anaemia on gas diffusion in the lungs. The NO and CO transfer factors of the lung (TLNO and TLCO) were measured, simultaneously, in 15 patients haemodialysed three times a week for 1-10 yrs. Assuming that NO is highly reactive with blood, Tlno is thus directly proportional to the membrane diffusion factor (DmCO). The lung capillary blood volume (Vc) was derived from the set of the two transfer equations. Transfer factors were measured between haemodialysis sessions. All patients but one were anaemic, with haemoglobin concentrations ranging 61-151 g.l-1. All had decreased Vc, and a decreased DmCO was observed in 14 patients. However, after correction for the anaemia, Vc values were normal with the exception of three patients. The percentage decrease in DmCO with respect to normal was correlated with the time elapsed since the first haemodialysis. These results support the idea of a progressive development of haemodialysis-induced chronic lung disease, that may be related to a mechanism of complement activation by a bio-incompatible membrane (Cuprophane). Accordingly, patients with compromised cardiopulmonary functions should be dialysed with a bio-compatible membrane.

Particle size effects on colloidal processing of oxide powders

Rheological behavior, properties of colloidal solids consolidated by filtration, and their structure change during drying were studied with aqueous suspensions of a mullite powder of nanometer size and two kinds of alumina powders of submicrometer sizes. The rheological properties of non-Newtonian flow suspensions were analyzed by a power law equation of S = K γn, where S is the shear stress, γ the shear rate, and K and n (O ⋚ n ⋚ 1) constants. The critical solids content (Vc) at n = O (indicating colloidal solids) depended greatly on the zeta potential of particles in suspensions, and dominated the densities of dried green compacts (Vg) of submicrometer sized powders. In a nanometer sized powder, the densities of dried green compacts were dependent on both Vc value and the solid contents of suspensions. Phase diagrams of one-component colloidal systems were constructed by plotting the Vc and Vg values against the zeta potential of particles. These phase diagrams indicate that the colloidal solids range (surrounded by Vc and a minimum Vg lines) is narrow for nanometer sized powder and wide for submicrometer sized powder. The solids content range of dried green compacts was very narrow for submicrometer sized powder but relatively wide for nanometer sized powder due to the low flexibility of colloidal structure during drying.

Study of functional and biochemical indicators of subclinical lung damage in bleomycin-treated patients

In 30 patients affected by testicular non-seminomatous cancer we evaluated pulmonary function tests before and after bleomycin-including combination chemotherapy. We paid particular attention to changes in diffusing lung capacity (DCO) and its two components, namely diffusing capacity of the alveolar-capillary membrane (Dm) and pulmonary capillary blood volume (Vc). In the same patients we also evaluated the behaviour of serum procollagen III aminopeptide (sP-III-P), assumed to be a biochemical equivalent to Dm, and of serum angiotensin converting enzyme (S-ACE), assumed to be a biochemical equivalent to Vc. We found that, after chemotherapy, patients showed a significant decline in several pulmonary function parameters, namely VC, TLC, and FEV1 (P < 0.0001, P = 0.0351, P = 0.0004, respectively), when compared to pre-treatment values. DCO was significantly impaired after chemotherapy (P < 0.0001), but with regard to its components, Vc values showed a significant decline (P = 0.0002), whereas Dm values were unchanged. Values of sP-III-P raised significantly after chemotherapy (P = 0.003), whereas S-ACE activity did not show any significant variation. When we looked at relationships between functional and biochemical parameter variations, the only significant correlation we found was between DCO and S-ACE (r2 = 0.112; P < 0.02). We conclude that in asymptomatic patients treated by bleomycin-including combination chemotherapy, DCO impairment is likely to occur because of a subclinical injury to pulmonary vessels, as suggested by Vc decline. Although the occurrence of pulmonary interstitial fibrosis after chemotherapy was excluded by chest X-ray examination and by stable values of Dm, sP-III-P elevation would suggest an accelerated type III collagen turnover in interstitial fibroblasts activated by bleomycin.

Determination of the Dimerization Constant in Self-Associating Systems

Abstract The self-association of Methylene Blue (MB), a cholic acid derivative, chlorpromazine hydrochloride (CPZ), and octaethylene glycol decyl ether has been investigated by frontal gel filtration chromatography (GFC) and spectrophotometry at 25 °C. The stepwise aggregation constant ki is estimated as a function of aggregation number i from the centroid volume Vc of the GFC profile by using appropriate association models. The dimerization constants k2 for MB and CPZ determined by spectrophotometry are close to those from Vc values. The dimerization constants are also estimated from the concentration dependence of the peak volume Vp of the derivative GFC profile. The k2 values determined from the Vp values are slightly larger than those from the Vc values. This discrepancy is ascribed to the approximation of the Vp approach. The minimum multimerization concentration (mmc), above which multimers higher than trimer are formed, is determined from each of Vc, Vp, and absorption spectral measurements. The relation between mmc and the critical micelle concentration (cmc) depends on the degree of criticalness of cmc. This degree of criticalness increases as the aggregation number at the maximum ki value increases.

On Nature of the High Frequency Cutoff in Pulsar Radio Spectra

AbstractUsing values of the frequencies vc for the high-frequency cutoffs of 31 pulsars obtained by other authors, we confirmed the relationship (obtained by us earlier) between vc and the period of pulsar P. The plot vc(χ) was drawn where χ is the relative angular distance between the line of sight and the center of the radiation cone. It is shown that pulsars with long periods cluster in the lower left corner of this diagram. Some geometrical and physical reasons causing high-frequency cutoffs are analyzed. The results can be explained by a model of thin plasma sheets. The interaction of these sheets causes generation of Langmuir waves at distances ~108 cm from the center of the neutron star. Pulsars without high-frequency cutoffs can be described by a model in which vc is very near the frequency of maximum in the spectra of these pulsars.