Physiological determinants of the pulmonary filtration coefficient

Current emphasis on translational application of genetic models of lung disease has renewed interest in the measurement of the gravimetric filtration coefficient (K(f)) as a means to assess vascular permeability changes in isolated perfused lungs. The K(f) is the product of the hydraulic conductivity and the filtration surface area, and is a sensitive measure of vascular fluid permeability when the pulmonary vessels are fully recruited and perfused. We have observed a remarkable consistency of the normalized baseline K(f) values between species with widely varying body weights from mice to sheep. Uniformity of K(f) values can be attributed to the thin alveolar capillary barrier required for gas exchange and the conserved matching of lung vascular surface area to the oxygen requirements of the body mass. An allometric correlation between the total lung filtration coefficient (K(f,t)) and body weight in several species (r(2)=1.00) had a slope that was similar to those reported for alveolar and pulmonary capillary surface areas and pulmonary diffusion coefficients determined by morphometric methods in these species. A consistent K(f) is dependent on accurately separating the filtration and vascular volume components of lung weight gain, then K(f) is a consistent and repeatable index of lung vascular permeability.     

Canine pulmonary angiotensin-converting enzyme. Physicochemical, catalytic and immunological properties.

Antiontensin-converting enzyme (peptidyldipeptide hydrolase, EC 3.4.15.1) has been solubilized from canine pulmonary particles and purified to apparent homogeneity. A value of approx. 140000 was estimated for the molecular weight of the native and the reduced, denatured forms of the enzyme. No free NH2-terminal residue was detected by the dansylation procedure. Carbohydrate accounted for 17% of the weight of the enzyme, and the major residues were galactose, mannose and N-acetylglucosamine with smaller amounts of sialic acid and fucose. Removal of sialic acid residues with neuraminidase did not alter enzymatic activity. The enzyme contained one molar equivalent of zinc. Addition of this metal reversed stimulation and inhibition of activity observed in the presence of Co2+ and Mn2+, respectively. Immunologic homology of pure dog and rabbit enzymes was demonstrable with goat antisera. Fab fragments and intact IgG antibodies displayed similar inhibition dose vs. response curves with homologous enzyme, whereas the fragments were poor inhibitors of heterologous activity compared to the holoantibodies. The canine glycoprotein was much less active than the rabbit preparation in catalyzing hydrolysis of Hip-His-Leu. In contrast, the two enzymes exhibited comparable kinetic parameters with angiotensin I as substrate.     

Brain weight correlations calculated from original results of Paul Broca

Anthropometric data collected by Professor Broca about a century ago is analyzed by modern statistical techniques. Brain weight is correlated positively with stature, negatively with age, length of stay in hospital and perhaps occupational levels. Correlations with age and between anatomical brain components are generally higher in women.     

Theory of optical ellipsometric measurements from muscle diffraction studies.

A theory of optical ellipsometry describing the complete phase shift and ellipticity of light diffracted from a single muscle fiber is developed. We show that both the phase shift information, described commonly by the birefringence of the fiber, and the ellipticity information, described by the differential polarizability ratio, are necessary to provide a complete picture of the complex contributions to the total optical anisotropy spectra from a diffraction pattern derived from the striated muscle cell. Both form and intrinsic contributions play significant roles in either the birefringence measurement or the differential field ratio measurement. However, we show that their relative weights in these two measured quantities are different, and measuring both of these parameters is necessary to obtain a more complete assessment of the cross-bridge structure and dynamics. The theoretical results have been tested for three different situations: solvent index matching, passive stretch of a resting fiber, and cross-bridge changes under isometric conditions. Comparisons between experimental data and simple model calculations provide much information regarding cross-bridge orientation and structure.     

The ultrastructure of frog mesenteric capillaries of known filtration coefficient.

The capillaries of the frog mesentery were investigated by transmission electronmicroscopy. The mean diameter of these vessels was 20 micrometers and a single layer of five to six endothelial cells (on average) contributed to each circumference. Their ultrastructure was very similar to that of mammalian capillaries of the continuous type [Bennett, Luft and Hampton, 1959]. The endotherlial cells, which contained many vesicles, were joined by specialized junctions and surrounded by a continuous basement membrane. Eleven capillaries were examined after the filtration coefficient of their walls had been investigated by the microperfusion micro-occlusion technique of Michel, Mason, Curry and Tooke [1974]. No abnormal appearances were observed even after the vessels had been perfused with protein free solutions which have been shown to increase filtration coefficient five fold. No morphological differences between capillaries were seen to accompany large differences in the filtration coefficients.     

The relationship between mean channel selection and the calculated coefficient of variation

Calculated coefficients of variation (CV) taken from the quotient of the standard deviation (S.D.) and the mean value of measured distributions are often used as an indicator of system performance in linear flow cytometry (FCM). The ability of the calculated CV to estimate the true CV of the underlying experiment before grouping (channelization) is dependent on the relationship between the width of the data channels and the magnitude of the S.D. of the measured distribution. When the channel width is equal to the S.D. of a distribution, the calculated CV is approximately 20% larger than the true CV of an experiment. By the time the S.D. is only one-half of a channel width, the calculated CV is unreliable. When the distribution S.D. is narrower than a channel's width, small changes in the distribution mean value will cause large variations in the calculated CV. As the true CV decreases, the calculation must be made with higher mean channel values. This dependence of calculated CV accuracy upon the relationship between S.D. and channel width places limitations upon mean channel selection that must be considered when using CV calculations for evaluating system performance, especially when looking for small improvements during optical alignment procedures. When an instrument is assumed to have a constant CV and the data are collected linearly, it is possible to improve the CV estimation accuracy by placing distributions in higher-numbered channels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ribonucleic acid from the higher plant Matthiola incana. Molecular weight measurements and DNA-RNA hybridisation studies.

The percentage of DNA from the crucifer Matthiola incana coding for different types of RNA was measured by filter saturation hybridisation experiments using RNA labelled in vivo. In addition, the melting curves of the various DNA - RNA hybrids formed and the buoyant densities of the DNA sequences complementary to different types of RNA were measured. 1. The RNA preparations used were 25, 18, and 5 S rRNA and 4 S RNA, purified by gel electrophoresis, and poly(A)-containing RNA purified by oligo-(dT)-cellulose chromatography. The molecular weights of the 25 S and 18 S rRNAs, calculated from the mobility in formamide-acrylamide gels relative to Escherichia coli RNA, are 1.25 - 10(6) and 0.64 - 10(6). The rRNA precursor has a molecular weight of approx. 2.1 - 10(6) and the average molecular weight of the poly(A)-containing RNA from both cotyledons and roots is 4 - 10(5). 2. The percentage of the genome, calculated on the basis of double-stranded DNA, coding for these RNAs and the estimated number of genes per haploid DNA amount are approximately 0.46% and 1100 for 25 S plus 18 S rRNA, 0.032% and 3600 for 5 S rRNA and 0.072% and 13 000 for 4 S RNA. In filter hybridisation experiments very little hybridisation of poly(A)-containing RNA was found. A rapidly-hybridising component is attributed to small amounts of contaminating rRNA. 3. M. incana DNA has a main band at 1.697 g - ml-1 in CsCl and a satellite constituting approximately 3% of the DNA, at 1.708 g - ml-1 - 25 and 18 S rRNA hybridise to DNA with a buoyant density of 1.701--2 g - ml-1. The buoyant density of 5 S DNA is slightly less at 1.700--1 g - ml-1. 4. S RNA hybridises to at least two separate regions, one within the main-band DNA and a second lighter component. None of the RNAs tested hybridised to the satellite DNA. The Tm of the DNA - RNA hybrids in 1 X SSC is 89 degrees C for 25 S rRNA, 85 degrees C for 5 S rRNA and 82 degrees C for 4 S RNA. 4. 5 and 4 S RNA preparations contain fragments which hybridise to sequences complementary to high-molecular-weight rRNA. This spurious hybridisation can be eliminated by competition with unlabelled high-molecular-weight RNA.     

Bacteriophage phiNS11: a lipid-containing phage of acidophilic thermophilic bacteria. IV. Sedimentation coefficient, diffusion coefficient, partial specific volume, and particle weight of the phage.

The particle weight (molecular weight) of phiNS11 was determined from the sedimentation coefficient, diffusion coefficient, and partial specific volume of the phage. The sedimentation coefficient of the phage (S(0)20, W) is 416 +/- 2.7S. The diffusion coefficient D(0)20, W), which was determined by quasielastic light scattering measurement, is (0.57 +/- 0.03) x 10(-7) cm2/s. The partial specific volume was determined by the mechanical oscillation technique to be 0.747 +/- 0.007 cm3/g. Based on these values, the particle weight of the phage was calculated to be (70.3 +/- 4.3) x 10(6) daltons, which agrees well with the particle weight (69--72 x 10(6) daltons) estimated from the molecular weight of phage DNA and the content of DNA. The Stokes radius of the phage particle was calculated to be 37.7 +/- 2 nm and hydration of the phage was estimated to be 1.18 cm3/g of dry phage. From the particle weight and the chemical composition of the phage, we estimated that one phage particle contains one double-stranded DNA molecule, 16,000 residues of fatty acid, 72 protein I molecules, 920 protein II, 42 protein III, 48 protein IV, 290 protein V molecules, and 3,700 molecules of polyamines.     

Calculation of the reflection coefficient from measurements of endogenous vascular indicators

The solvent drag reflection coefficient (sigma) for total proteins can be estimated by comparing the relative degrees of concentration of erythrocytes and plasma proteins that occur during fluid filtration in an isolated perfused organ. In this analysis, we evaluated the accuracy of equations proposed by Pilati and Maron [Am. J. Physiol. 247 (Heart Circ. Physiol. 16): H1-H7, 1984] and Wolf et al. [Am. J. Physiol. 253 (Heart Circ. Physiol. 22): H194-H204, 1987] to calculate sigma from these concentration changes. We calculated sigma with each equation using data generated from a mathematical model of fluid and solute flux in membranes with known sigma's. We found that the equation of Wolf et al. provided the closest approximation to the true sigma over the entire range of filtration fractions tested (0.1-0.6), with the differences between the two equations increasing with filtration fraction. At low filtration fractions, the difference in sigma obtained using either approach was found to be inconsequential. At larger filtration fractions, a closer approximation of the true sigma can be obtained using the equation of Wolf et al.     

Polymeric C-terminal cross-linked material from type-I collagen. A modified method for purification, anomalous behaviour on gel filtration, molecular weight estimation, carbohydrate content and lipid content.

Polymeric cross-linked C-terminal peptide material (poly-alpha 1CB6) from mature bovine tendon type-I collagen was prepared and purified by a modification of the method previously described [Light & Bailey (1980) Biochem. J. 185, 373-381]. Poly-alpha 1CB6 was shown to exhibit concentration-dependent aggregation effects on gel filtration due to interaction with a filtration medium. The material had an amino acid content that was very similar to a mixture of alpha 1CB6 and alpha 1CB5. The material was shown to be polydisperse with a mol.wt. range of 50 000-350 000, but chromatographic fractions were relatively homogeneous over this molecular weight range with respect to amino-acid composition. The heterogeneity of the material was not due to incomplete CNBr peptide cleavage, as poly-alpha 1CB6 did not contain detectable quantities of methionine. The material showed no discrete bands on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis but gave a constant blue stain throughout the molecular weight range described above. Lipid analysis showed that the partially purified material contained elevated levels of stearate when compared to the crude CNBr-digested starting material. This may indicate the specific association of a stearic-acid-rich lipid with the peptide material. On carbohydrate analysis poly-alpha 1CB6 was shown to contain only galactose and glucose at levels of 0.72 and 0.28% respectively. The carbohydrate and amino acid analyses indicated that (alpha 1CB6)2-(alpha 1CB5)1 may be the basic cross-linked structural unit of poly-alpha 1CB6)2-(alpha 1CB5)1 units, although the carbohydrate analysis indicated that the higher molecular weight oligomers may be enriched in alpha 1CB6.     

Blood flow vs. venous pressure effects on filtration coefficient in oleic acid-injured lung

On the basis ofchanges in capillary filtration coefficient(K_fc) in 24 rabbit lungs, we determined whether elevations in pulmonary venouspressure (Ppv) or blood flow (BF) produced differences infiltration surface area in oleic acid-injured (OA) or control (Con)lungs. Lungs were cyclically ventilated and perfused under zone 3 conditions by using blood and 5% albumin with no pharmacological modulation of vascular tone. Pulmonary arterial, venous, and capillary pressures were measured by using arterial, venous, and double occlusion. Before and during eachK_fc-measurementmaneuver, microvascular/total vascular compliance was measured by usingvenous occlusion.K_fc was measuredbefore and 30 min after injury, by using a Ppv elevation of 7 cmH₂O or a BF elevation from 1 to2 l · min¹ · 100 g¹ to obtain a similardouble occlusion pressure. Pulmonary arterial pressure increased morewith BF than with Ppv in both Con and OA lungs [29 ± 2 vs. 19 ± 0.7 (means ± SE) cmH₂O;P < 0.001]. In OA lungscompared with Con lungs, values ofK_fc (200 ± 40 vs. 83 ± 14%, respectively; P < 0.01) and microvascular/total vascular compliance ratio (86 ± 4 vs. 68 ± 5%, respectively; P < 0.01) increased more with BF than with Ppv. In conclusion, for a given OA-induced increase in hydraulic conductivity, BF elevation increased filtration surface area more than did Ppv elevation. The steep pulmonary pressure profile induced by increased BF could result in therecruitment of injured capillaries and could also shift downstream thecompression point of blind (zone 1) and open injured vessels (zone 2).

     

Rapid filtration measurements of Ca2+ release from cisternal sarcoplasmic reticulum vesicles

A radioactive tracer and rapid filtration method was applied to the study of Ca2+ release from sarcoplasmic reticulum (SR) vesicles which were preloaded passively (equilibration with millimolar Ca2+) or actively (in the presence of ATP or acetyl phosphate). The method allows complete substitution of the loading mixture with release medium in constant flow, and time resolution between 0.01 and 10.0 s. Net release can be clearly distinguished from isotope exchange. The latter is prominent in longitudinal SR vesicles. Net Ca2+ release is observed only from cisternal SR vesicles, is Ca2+ (micromolar) dependent, and is accelerated by inactive ATP analogues, or ATP itself, even in the presence of Mg2+. Net release has a strong pH dependence (between 6 and 7), and very little temperature dependence (consistent with a passive channel). In media of physiological significance (1 mM ATP, 1 mM magnesium, and free Ca2+ in the micromolar range), net Ca2+ release proceeds with a rate constant of approx. 100 s-1.     

Alterations of filtration coefficients in pulmonary edema of different pathogenesis.

Different pathomechanisms in the development of pulmonary edema are being discussed. We investigated the effect of pathogenetically varying forms of edema on lung vascular barrier function in isolated cell-free perfused rabbit lungs. As an index of permeability, capillary filtration coefficients (Kfc) were determined from the slope of lung weight change over periods of stepwise venous pressure elevation (5, 7.5, and 10 mmHg) before (controls) and 60 min after edema induction. Edema was induced by venous congestion (n = 6), by application of arachidonic acid in the presence of diclofenac sodium (n = 6), and by elastase application (n = 6). Control values ranged from 0.28 to 0.51 ml.min-1 x mmHg-1 x 100 g-1. Kfc was significantly enhanced after edema induction up to 243% of control value in the hydrostatic edema, 357% in the arachidonic acid edema, and 594% in the elastase edema. When the alterations in capillary filtration due to the different types of edema were compared, Kfc was significantly higher in the proteinase edema, indicating an irreversibly damaged barrier function. These data exemplify different pathophysiological characteristics due to the pathogenesis of interstitial edema formation.