Monoclonal antibodies to surfactant proteins SP28-36 label canine type II and nonciliated bronchiolar cells by immunofluorescence

The major 28,000- to 36,000-dalton proteins of pulmonary surfactant (SP28-36) have been shown by various techniques to be synthetic and secretory products of alveolar type II cells. Surfactant lipids are also secreted by these cells. Immunocytochemical studies of human and rodent lungs have indicated that nonciliated epithelial cells of small bronchioles appear to contain SP28-36 in their synthetic organelles and secretory granules. Because these observations were obtained with polyclonal antibodies against SP28-36, it was possible that bronchiolar cell staining was due to contaminant antibodies not detected by biochemical analyses. To clarify the role of bronchiolar cells in the metabolism of SP28-36, we have prepared 5 monoclonal antibodies against canine SP28-36. Electrophoresis and immunoblots of surfactant showed that each antibody reacted with SP32 and 36, as well as SP28, the nonglycosylated species. This indicates that the antibodies are directed against the protein rather than carbohydrate moieties of SP28-36. Immunoblot analysis of collagenase-treated SP28-36 showed that the antibodies DS-3 and DS-1 were directed against the noncollagen region of the protein. Immunoblot analysis of whole canine lung homogenates showed that a single protein species was recognized by the antibodies. Immunofluorescence studies of cryostat sections of canine lung showed that both type II and nonciliated bronchiolar cells were specifically labeled with each antibody. These and previous data are consistent with and support the idea that bronchiolar cells synthesize and secrete SP28-36.

Temporal order judgements in good and poor readers

The amount of time required to make accurate (75% correct) temporal order judgements was measured in groups of 3rd and 4th grade children who were selected on the basis of reading ability. The stimuli, two words (Box and Fox), were tachistoscopically presented to the left and right or above and below a fixation point. Subjects were asked to say which word came first under one condition, or which position contained the stimulus that occurred first under another condition. The stimulus onset asynchrony (SOA) was varied in half octave steps until threshold was determined. The results indicate that good readers required significantly longer SOAs to achieve 75% correct than adults, but significantly shorter SOAs than poor readers. There was not a significant difference in thresholds for the word and position conditions for adults or good readers, but poor readers required significantly more time to achieve criterion for the word condition. The word thresholds were highly correlated (-0.77) with reading level, but the correlation between position threshold and reading level was not significant. The implications of a temporal order deficit are discussed.

Divalent cation and hydrogen ion effects on the structure and surface activity of pulmonary surfactant

The structure and surface activity of the extracellular fraction of pulmonary surfactant known as tubular myelin are Ca2+ dependent. Previous studies have demonstrated surfactant-specific proteins with monomeric molecular weights of 28,000-36,000 (SP28-36) are associated with this fraction. In reassembled lipoprotein mixtures, SP28-36 promotes the Ca2+-induced aggregation and surface activity of surfactant lipids, but the detailed interactions between Ca2+, SP28-36, and surfactant lipids have not been established. In this study, we investigated the effect of various cations on the aggregation of surfactant lipid liposomes in the presence of SP28-36. SP28-36 reduced the threshold ion concentration for liposome aggregation from greater than 10 to 0.5 mM for Ca2+, Ba2+, and Sr2+ but not Mg2+ or Mn2+. The liposome aggregation was reversed by ethylenediaminetetraacetic acid and not associated with leakage of carboxyfluorescein. SP28-36 promoted similar liposome aggregation at pH less than 5 in the absence of divalent cations. Surfactant lipids adsorbed slowly to an air-fluid interface in all ionic conditions unless SP28-36 was present. Both Ca2+ and H+ induced rapid lipid adsorption in the presence of SP28-36. The surface activity of native surfactant had a similar ion dependence. Electron micrographs of native surfactant showed typical tubular myelin structures at pH 7.4 only in the presence of Ca2+. At pH 4.4 in the absence of Ca2+, similar but not identical structures were seen. In the reconstituted system, SP28-36 in the presence of Ca2+ induced the formation of larger multilayered structures including parallel bilayers and small areas of squares and triangles with dimensions similar to structures found in the native material.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathological findings in a natural outbreak of aflatoxicosis in dogs

The gross and histopathological lesions of 10 cases in a natural outbreak of aflatoxicosis amongst dogs in the Republic of South Africa are reported. The 10 cases were classified as acute (1 case), subacute (7 cases) and chronic (2 cases) on the basis of the nature, degree and extent of the following histopathological fractures: hepatocellular fatty degeneration, necrosis or regeneration; proliferation of bile ductules; accumulation of bile within the canaliculi; fibroplasia; and, mucoid degeneration, necrosis or segmental atrophy of the larger intrahepatic bile ducts. Fatty degeneration was noted grossly in the livers of all 10 cases and bile stasis in 4. Varying degrees of fibrosis were present depending on the stage of the disease. In the 2 chronic cases in which nodular regeneration was also observed fibrosis was pronounced. Other macroscopic findings included icterus, anaemia, ascites, hydrothorax, hydropericardium, anasarca, pulmonary oedema, gastro-enterorrhagia and nephrosis.

Quantitation of baboon lipoproteins by high performance gel exclusion chromatography

High performance liquid chromatography with gel exclusion columns was used for quantitative measurement of plasma lipoproteins. A combination of columns TKS 4000 PW and 3000 PW gave good separation of very low (VLDL), low (LDL) and high (HDL) density lipoproteins. The area under each lipoprotein peak detected by absorbance at 280 nm was measured by digitizing and was expressed as cm2. Purified lipoprotein standards isolated by ultracentrifugation were also chromatographed in increasing concentrations. The area under the lipoprotein standard peak was linearly related to the amount of total protein over a wide range. The areas of most of the measured plasma lipoproteins were within the linear range. The relationship between the area and the amount of protein for each standard was used to quantitate the amount of protein and was expressed as mg/dl plasma. This technique is simple and requires a small amount of plasma. The validated technique was applied to a large population of pedigreed baboons. An average plasma lipoprotein profile of feral baboons on the chow diet was characterized by a high level of HDL (90.9 +/- 30.7 mg/dl) with a lesser amount of LDL (29.1 +/- 13.2 mg/dl). VLDL was present in much lower concentration (8.6 +/- 2.6 mg/dl). Feeding a high cholesterol and high saturated fat (HCHF) diet raised both LDL (1.5-fold) and HDL levels (1.3-fold) without changing VLDL levels. Progeny of sires with low response to dietary cholesterol increased their HDL protein when challenged with HCHF diet without any change in their LDL or VLDL.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and characterization of differentiated alveolar type II cells from fetal human lung

A method has been developed for isolating differentiated type II cells from human lung of 18-24-week gestation. The procedure involves an initial 4-day culture of lung explants in the presence of dexamethasone (10 nM) and triiodothyronine (2 nM). Type II cells (and fibroblasts) are isolated by trypsin digestion of the explants, two differential adherence steps and incubation overnight in primary culture. This method provides a high yield of type II cells ((50 +/- 15) X 10(6) cells/g wet weight of explant) with a purity of 85 +/- 5% in 16 experiments. The type II cells contain numerous perinuclear granules which stain darkly with toluidine blue and Papanicolaou stain; electron microscopy showed these inclusions to be lamellar bodies with tightly stacked, well defined lamellae. Type II cells, but not fibroblasts, were positive by immunofluorescence histology for surfactant apoprotein and binding of Maclura pomifera lectin which binds to the surface of type II but not type I cells in vivo. The rate of both [3H]acetate and [3H]choline incorporation into phosphatidylcholine (PC) was several-fold greater in type II cells than fibroblasts; the saturation of PC was 36.2 and 25.9%, respectively. Release of saturated PC was stimulated by terbutaline, the ionophore A23187, and tetradecanoyl phorbol acetate in type II cells but not fibroblasts. We conclude that differentiated type II cells can be isolated in relatively high yield and purity from hormone-treated explants of fetal human lung.

Immunocytochemical localization of the major surfactant apoproteins in type II cells, Clara cells, and alveolar macrophages of rat lung

The adsorptive properties of phospholipids of pulmonary surfactant are markedly influenced by the presence of three related proteins (26-38 KD, reduced) found in purified surfactant. Whether these proteins are pre-assembled with lipids before secretion is uncertain but would be expected for a lipoprotein secretion. We performed indirect immunocytochemistry on frozen thin sections of rat lung to identify cells and intracellular organelles that contain these proteins. The three proteins, purified from lavaged surfactant, were used to generate antisera in rabbits. Immunoblotting of rat surfactant showed that the IgG reacted with the three proteins and a 55-60 KD band which may be a polymer of the lower MW species. Specific gold labeling occurred over alveolar type II cells, bronchiolar Clara cells, alveolar macrophages, and tubular myelin. In type II cells labeling occurred in synthetic organelles and lamellar bodies, which contain surfactant lipids. Lamellar body labeling was increased fivefold by pre-treating tissue sections with a detergent. Multivesicular bodies and some small apical vesicles in type II cells were also labeled. Secondary lysosomes of alveolar macrophages were immunoreactive. Labeling in Clara cells exceeded that of type II cells, with prominent labeling in secretory granules, Golgi apparatus, and endoplasmic reticulum. These observations clarify the organelles and pathways utilized in the elaboration of surfactant. After synthesis, the proteins move, probably via multivesicular bodies, to lamellar bodies. Both lipids and proteins are present in tubular myelin. Immunologically identical or closely similar proteins are synthesized by Clara cells and secreted from granules which appear not to contain lipid. The role of these proteins in bronchiolar function is unknown.

Effect of tolazamide on basal ketogenesis, glycogenesis, and gluconeogenesis in liver obtained from normal and diabetic rats

The effect of tolazamide on in vitro rates of gluconeogenesis, ketogenesis, and glycogenesis was determined in liver tissue from fasted normal and diabetic rats. Hormones were not added to the incubation mixture. Two concentrations of the drug were tested, one of which was therapeutic (40 micrograms/ml) and other immoderately elevated (400 micrograms/ml). Neither drug concentration affected hepatic glycogen synthesis. However, the low dose of tolazamide inhibited ketogenesis in the diabetic liver by 39% and in the control liver by 32%; oxidative CO2 production from palmitate was reduced in parallel with ketogenesis. The drug did not alter ketogenesis in isolated intact mitochondria. Similarly, this same therapeutic dose curtailed hepatic gluconeogenesis only in control liver (74% inhibition); this reaction was unaltered by this drug concentration in the explants derived from the diabetic rats. The logarithmically higher dose inhibited hepatic gluconeogenesis in both control and diabetic liver tissue by 56% and 51%, respectively. Hence, possibly acting at a postreceptor site, therapeutic concentrations of tolazamide can decrease rat hepatic in vitro gluconeogenesis and ketogenesis.

The effects of antibiotics on hemolytic behavior of red cells

Human blood was sheared between rotating polyethylene disks and plasma hemoglobin measured at intervals to produce kinetic hemolysis curves (KHC), plotted as free hemoglobin concentration vs time. The KHC produced by blood samples incubated in the presence of penicillin, streptomycin, gentamicin, and amikacin lie always below those for control samples, indicating a reduction in hemolysis; this reduction was greater as the drug concentration was increased. Explanations in terms of alterations in red cell structure were sought by several characterization tests of amikacin-loaded blood samples. Drug-localization studies demonstrated that significant fractions of the total dosage were associated with the red-cell membrane. Resistive pulse spectroscopy was used to show how amikacin affected cell size, deformability, and osmotic fragility; results were sensitive to storage age of the blood. In all cases, the effect of shearing was to reduce cell size, deformability, and osmotic fragility. Mechanisms for hemolytic protection by drugs are proposed.

An improved method for isolating type II cells in high yield and purity

A method has been developed for isolating alveolar type II cells by digesting lung tissue with elastase and "panning" the resultant cell suspension on plates coated with IgG. This method provides both high yield and purity of type II cells. In 50 experiments with rats, we obtained 35 +/- 11 X 10(6) cells/rat, 89 +/- 4% of which were type II cells (mean +/- SD). Type II cells isolated by "panning" adhered more rapidly and completely in tissue culture than did cells isolated by centrifugation over discontinuous density gradients of metrizamide. The "panning" method is superior to other methods for isolating type II cells in that it provides a population of type II cells of both high yield and high purity. The method is fast, reproducible, and easily adaptable to isolating type II cells from species other than rats.

Glucocorticoids and thyroid hormones stimulate biochemical and morphological differentiation of human fetal lung in organ culture

We characterized the stimulatory effects of both glucocorticoids and thyroid hormones on the surfactant system in human fetal lung. Synthesis of phosphatidylcholine (PC) and morphology were examined in explant cultures (15-24 weeks gestation) maintained 1-7 days in serum-free Waymouth's medium in a 95%-air-5% CO2 atmosphere. Control explants (no hormones) had the same rate of choline incorporation into PC between 1 and 7 days, but a significant increase in tissue PC content [82 +/- 21%, (+/- SEM), day 6 vs. 1], consistent with slow turnover of PC. [3H]Choline incorporation was stimulated 36%, 137%, and 192% by T3 (2 nM), dexamethasone (Dex; 10 nM), and T3 plus Dex, respectively, after 6 days of exposure (optimal response) compared to 19%, 38%, and 84% after 2 days of exposure. Thus, a supra-additive response occurred in the presence of both hormones and was greater at a shorter exposure time. Dex increased the percent saturation of newly synthesized PC (28.9 +/- 0.9% vs. 17.8 +/- 0.8% for control), but T3 did not, whereas both hormones increased tissue PC content (74.4 +/- 7.3% and 18.7 +/- 7.8% increase vs. control, respectively). Pulse-chase experiments with [3H]choline suggest that remodeling of unsaturated PC to saturated PC occurred during culture and was stimulated by Dex. Incorporation of [3H]acetate and [3H]glycerol into PC was stimulated by Dex (830% and 77%, respectively), but not by T3; the distribution of incorporated radioactivity among phospholipids was changed by Dex (increased counts per min into PC and phosphatidylglycerol with acetate and glycerol, respectively), but not by T3. Half-maximal stimulation of choline incorporation occurred at concentrations of Dex (2.1 nM) and T3 (0.03 nM) that are similar to the Kd values for receptor binding (5 and 0.05 nM, respectively). The relative potencies of thyroid hormones were T3 greater than T4 greater than rT3, and for corticosteroids, Dex much greater than corticosterone greater than 11-dehydrocorticosterone = cortisol greater than cortisone. Stimulation by either T3 or cortisol was reversed within 24-48 h of hormone removal. Initial treatment of explants with Dex enhanced the subsequent response to T3, but not vice versa. Culture for 4-5 days in the absence of hormones produced some morphological maturation of the epithelial cells, whereas treatment with T3 plus Dex markedly increased the number and size of lamellar bodies in epithelial cells, caused extensive proliferation of apical microvilli, and reduced glycogen deposits. Our findings are consistent with receptor-mediated stimulation of surfactant synthesis in human lung by both glucocorticoids and thyroid hormones.(ABSTRACT TRUNCATED AT 400 WORDS)

Rapid method for measuring plasma low-density lipoprotein turnover using high-performance gel exclusion chromatography

High-performance gel exclusion chromatography using flow-through radioactivity monitoring was employed for rapid measurement of low-density lipoprotein (LDL) turnover. Iodinated LDL was injected into five fasting rabbits. Serial blood samples were obtained and small aliquots (0.1-0.2 ml) were injected into the chromatographic system using 0.2 M Tris-acetate buffer (pH 7.0). Radioactivity in lipoproteins was measured by an on-line gamma counter (Flo-One) attached to the high-performance liquid chromatograph and in a regular gamma counter after collecting the fractions. Sequential ultracentrifugation was also used to separate lipoproteins, and the radioactivity in each fraction was measured. The Flo-One method was faster; however, the efficiency of Flo-One varied with the amount of radioactivity and therefore it was necessary to inject the same amount of radioactivity to get comparable values.

Antioxidant enzyme activity in alveolar type II cells after exposure of rats to hyperoxia

The activity of antioxidant enzymes were measured in alveolar type II cells isolated from control and 85% oxygen-exposed rats to determine if type II cells, an oxygen-resistant lung cell type had constitutively high enzyme activities and to measure the effect of hyperoxia on these antioxidant enzyme. Type II cells were isolated from lungs of control rats and rats exposed to 85% O2 for 7 days. In whole lungs of rats exposed to 85% oxygen there is an increase in activity (per lung or per mg lung DNA) in the antioxidant enzymes CuZn superoxide dismutase, Mn superoxide dismutase, catalase, glutathione peroxidase and glucose-6-phosphate dehydrogenase. Oxygen exposure significantly increased (p less than 0.05) all type II cell antioxidant enzyme activities when expressed per mg DNA. The protein content of oxygen exposed type II cells increased 25% from (63.9 +/- 4.8 micrograms/10(6) cells to 79.6 +/- 4.2 micrograms/10(6) cells, p less than 0.05). When type II cell enzyme activities were expressed in U/mg cell protein, only CuZn superoxide dismutase and Mn superoxide dismutase increased in activity following oxygen exposure (by 43% and 28% relative to air exposed lung type II cells, respectively, p less than 0.05). This suggested that most lung cell antioxidant enzymes increased in activity following oxidant stress in proportion to increased cell mass. CuZn and Mn superoxide dismutase increased activity to an extent greater than the increase in type II cell protein content after oxygen exposure. Alveolar macrophages lavaged from control and oxygen-exposed rats were also evaluated, and they had no significant change in CuZn and Mn superoxide dismutase activities. Type II cells accounted for 10% and 17% of alveolar cells in control and oxygen treated rats. By knowing the antioxidant enzyme activities in type II cells, the total enzyme activity of whole lung and the number of type II cells in control and oxygen exposed rats from morphometric data, we calculated the percent of whole lung enzyme activity accounted for by type II cells. Type II cells accounted for a high percentage of lung glucose-6-phosphate dehydrogenase (58% in control rats, 65% in oxygen exposed rats) but a low percentage of Mn superoxide dismutase (4% in control rats, 6% in oxygen exposed rats).

Effects of blood storage on rheology and damage in low-stress shear flow

Data are presented on the rheological and hemolytic behavior of whole human blood as it ages while stored at 4 degrees C (as in blood banking practice) up to 26 days. The viscometric properties of steady shear viscosity eta and oscillatory (complex) viscosity eta * = eta' - i eta" reported over ranges of shear rate gamma and radian frequency omega of 33 less than gamma less than 4130 s-1 and 1.5 less than omega less than 48 s -1; data on autologous plasma are given for reference. The Cox-Merz relation, eta (gamma) = [eta *(omega)] omega = gamma, is found to be a good approximation, with eta greater than or equal to [eta *], over the range studied. Release of hemoglobin (Hgb) and lactate dehydrogenase (LDH) into the plasma during shearing is tracked as a function of time for 30 min, and its sensitivity to gamma magnitude is measured. Bloods from four different donors are studied, with primary attention given to one (SSR). For all bloods, the release of both Hgb and LDH increases with storage age, but differences in such aging characteristics between different bloods can be substantial (even when rheological properties are identical). A post-shear incubation at 4 degrees C for one day shows no enhancement of plasma Hgb and LDH levels beyond those expected from normal aging after the shearing experience, demonstrating the absence of significant delayed-action effects as a consequence of shearing trauma.

Changes in biochemical characteristics and pattern of lectin binding of alveolar type II cells with time in culture

When cultured on plastic culture dishes for several days, alveolar type II cells gradually lose both their morphologic and biochemical identifying characteristics. Although type II cells cultured on a matrix derived from corneal endothelial cells have previously been reported to retain lamellar bodies for 7-10 days in culture, the ability of type II cells cultured on matrix to synthesize surfactant lipids has not been previously studied. We therefore measured the phospholipid content and the distribution of [14C]acetate into classes of lipids by type II cells maintained in culture. We found no differences between cells cultured on plastic or on matrix. We then studied the binding to type II cells in culture of Maclura pomifera and Ricinus communis I, lectins specific in vivo for type II and type I cells, respectively. We found that the cells progressively bind less M. pomifera and more R. communis I. The change in pattern of lectin binding occurs whether cells are cultured on plastic or matrix, whether lectins are conjugated with fluorescein, rhodamine or ferritin, or whether cells are cultured in the presence or absence of serum. We conclude that type II cells cultured on either tissue culture plastic or matrix derived from corneal endothelial cells lose the ability to synthesize and contain surfactant phospholipids, and, at least in their pattern of lectin binding, become similar to type I cells.

Identification of rat alveolar type II epithelial cells with a tannic acid and polychrome stain

Alveolar type II epithelial cells are identified by the presence of characteristic lamellar inclusions visualized by transmission electron microscopy. We developed a tannic acid and polychrome stain that can visualize these intracellular inclusions in rat alveolar type II cells by light microscopy and that can be used for autoradiography. This method of staining and fixation provides more cellular detail than other methods that use light microscopy.

Mortality of a white rhinoceros (Ceratotherium simum) suspected to be associated with the blue-green alga Microcystis aeruginosa

Three of four white rhinoceroses died within 3 months of introduction into a game reserve. Post-mortem examination of one of the animals revealed marked hepatomegaly with haemorrhage and severe necrosis of the liver as well as numerous ecchymoses and petechiae in the subcutaneous tissue and subserosa of the thorax, abdomen and diaphragm. Histologically, severe hepatic necrosis was the most significant finding. Algae recovered from the dam from which the animals drank were identified as Microcystis aeruginosa. A diagnosis of suspected Microcystis poisoning was made.

Intoxication in cattle, chicks and hamsters from seed of the palo santo tree (Bulnesia sarmientii)

A case of intoxication in cattle in Paraguay from seed of the palo santo tree is discussed. Visible toxic signs and lesions observed at necropsy are described. The seed contained 3.5 per cent or more crude saponin. Laboratory studies established that aqueous extracts and crude saponin from the seeds were toxic to one-week-old chicks and adult hamsters.