Search PubMed⌕ Search

Biomedical subjects

R J Mason

Publications and source records attributed to R J Mason.

At least 109 records · Page 6Linked to original sources
PubMed1993

Keratinocyte growth factor and hepatocyte growth factor/scatter factor are heparin-binding growth factors for alveolar type II cells in fibroblast-conditioned medium.

Epithelial-mesenchymal interactions mediate aspects of normal lung growth and development and are important in the restoration of normal alveolar architecture after lung injury. To determine if fibroblasts are a source of soluble growth factors for alveolar type II cells, we investigated the effect of fibroblast-conditioned medium (CM) on alveolar type II cell DNA synthesis. Serum-free CM from confluent adult human lung fibroblasts was concentrated fivefold by lyophilization. Type II cells were isolated from adult rats by elastase dissociation and incubated with [3H]thymidine and varying dilutions of concentrated CM and serum from day 1 to 3 of culture. Stimulation of type II cell DNA synthesis by fibroblast-CM was maximal after 48 h of conditioning and required the presence of serum. The activity of the CM was eliminated by boiling and by treatment with trypsin, pepsin, or dithiothreitol and was additive with saturating concentrations of acidic fibroblast growth factor, epidermal growth factor, and insulin. The growth factor activity bound to heparin-Sepharose and was eluted with 0.6 and 1.0 M NaCl. Neutralizing antibody studies demonstrated that the primary mitogens isolated in the 0.6 and 1.0 M NaCl fractions were keratinocyte growth factor (KGF, fibroblast growth factor 7) and hepatocyte growth factor/scatter factor (HGF/SF), respectively. HGF/SF was demonstrated in the crude CM and KGF was detected in the 0.6 M NaCl eluent by immunoblotting. Northern blot analysis confirmed that the lung fibroblasts expressed both KGF and HGF/SF transcripts. Human recombinant KGF and HGF/SF induced a concentration- and serum-dependent increase in rat alveolar type II cell DNA synthesis. We conclude that adult human lung fibroblasts produce at least two soluble heparin-binding growth factors, KGF and HGF/SF, which promote DNA synthesis and proliferation of rat alveolar type II cells in primary culture. KGF and HGF/SF may be important stimuli for alveolar type II cell proliferation during lung growth and after lung injury.

Animals↗
PubMed1993

Internalization of surfactant protein A (SP-A) into lamellar bodies of rat alveolar type II cells in vitro.

Pulmonary surfactant is thought to be internalized and processed for reuse by alveolar Type II cells. In the present study we followed the internalization and intracellular trafficking of purified surfactant protein A (SP-A) by primary cultures of alveolar Type II cells. Internalization of native rat SP-A was compared with that of recombinant rat and human SP-A isolated from a patient with alveolar proteinosis. All SP-A species were conjugated with colloidal gold for visualization by electron microscopy. The gold conjugates were biologically active, as demonstrated by inhibition of phospholipid secretion from alveolar Type II cells. The SP-A-gold conjugates were internalized to lamellar bodies (LB) via the endosomal system, which included both electron-lucent and -dense multivesicular bodies. Labeling of LB was time dependent, and after 7 hr 30-40% of these organelles were labeled. Alkylation of SP-A greatly reduced internalization, as did an excess of non-conjugated SP-A. No qualitative differences in uptake were observed with the three forms of SP-A. The percent of labeled LB was similar (30-40%) after 7 hr of internalization with the three species of SP-A. The recombinant SP-A produced using a baculovirus vector lacked hydroxyproline and had an altered oligosaccharide, but these features did not affect its internalization or the rate of LB labeling. Internalization of the gold-conjugated SP-A and endocytosis of the fluid-phase marker Lucifer Yellow were related to the shape of Type II cells. Both uptake of SP-A, which is receptor mediated, and fluid-phase endocytosis were found to be less active in the flattened than in the rounded cells. Therefore, cell shape and hence cytoskeletal organization may play an important role in SP-A recycling. However, it is possible that both morphology and decreased endocytosis are independent manifestations related to the loss of differentiated function of cultured Type II cells.

Animals↗
PubMed1992

Pulmonary surfactant secretion is regulated by the physical state of extracellular phosphatidylcholine.

Pulmonary alveolar type II cells synthesize, secrete, and recycle the components of pulmonary surfactant. In this report we present evidence that dipalmitoylphosphatidylcholine is a potent inhibitor of surfactant lipid secretion by type II cells. Monoenoic and dienoic phosphatidylcholines with fatty acids of 16 or 18 carbons are ineffective as inhibitors of surfactant lipid secretion. In contrast, disaturated phosphatidylcholines, with either symmetric or asymmetric pairs of fatty acids of 14, 16, or 18 carbons, exhibit inhibition of surfactant secretion that correlates extremely well with the phase transition temperature (Tc) of the phospholipid. The inhibitory activity of dipalmitoylphosphatidylcholine is not dependent upon lipid stereochemistry. N-Methylated derivatives of dipalmitoylphosphatidylethanolamine are significantly less effective than phosphatidylcholine as inhibitors. Phosphatidylcholines below their phase transition temperature are inhibitors of surfactant secretion, whereas those above their phase transition temperature are either ineffective or weakly inhibitory. The phase transition dependence of inhibition is observed when type II cells are incubated at 37 degrees C with different species of phosphatidylcholine. In addition, if type II cells are stimulated to secrete at different temperatures the efficacy of a given phospholipid as an inhibitor is dependent on its relationship to Tc (i.e. dipalmitoylphosphatidylcholine with a Tc of 41 degrees C significantly inhibits secretion at 37 degrees C but not at 42 degrees C). Inhibition of surfactant secretion by dipalmitoylphosphatidylcholine is abrogated when it is incorporated into the same liposome with dioleoylphosphatidylcholine as a 50:50 mixture. In contrast, the simultaneous addition of two separate populations of liposomes, one composed of dipalmitoylphosphatidylcholine and the other composed of dioleoylphosphatidylcholine, does not significantly alter the inhibitory activity found with dipalmitoylphosphatidylcholine alone. These data provide compelling evidence that the physical state of phosphatidylcholine can regulate surfactant secretion from alveolar type II cells and suggest a unique mechanism for regulating exocytosis in the alveolus of the lung.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1992

Primary structure of rat pulmonary surfactant protein D. cDNA and deduced amino acid sequence.

Surfactant protein D (SP-D) is a carbohydrate-binding glycoprotein containing a collagen-like domain that is synthesized by alveolar type II epithelial cells. The complete primary structure of rat SP-D has been determined by sequencing of a cloned cDNA. The protein consists of three regions: an NH2-terminal segment of 25 amino acids, a collagen-like domain consisting of 59 Gly-X-Y repeats, and a COOH-terminal carbohydrate recognition domain of 153 amino acids. There are 6 cysteine residues present in rat SP-D: 2 in the NH2-terminal noncollagenous segment and 4 in the COOH-terminal carbohydrate-binding domain. The collagenous domain contains one possible N-glycosylation site. The protein is preceded by a cleaved, NH2-terminal signal peptide. SP-D shares considerable homology with the C-type mammalian lectins. Hybridization analysis demonstrates that rat SP-D is encoded by a 1.3-kilobase mRNA which is abundant in lung and highly enriched in alveolar type II cells. Extensive homology exists between rat SP-D and bovine conglutinin.

Amino Acid Sequence↗
PubMed1992

Alterations in eicosanoid production by rat alveolar type II cells isolated after silica-induced lung injury.

Although alveolar type II cells in primary culture have been shown to produce eicosanoids and exposure of type II cells to silica in vitro alters eicosanoid production, the production of eicosanoids by alveolar type II cells isolated after acute lung injury in vivo has not been evaluated. Therefore, we investigated the production of arachidonic acid (AA) metabolites by alveolar type II cells isolated after silica-induced lung injury. Alveolar type II cells were isolated from rats 14 days after intratracheal silica instillation and from untreated animals. Type II cells were separated into normotrophic and hypertrophic populations by centrifugal elutriation, and secreted eicosanoids were determined under basal and stimulated conditions by enzyme immunoassay on the day of isolation and after 1 day in culture. Under basal conditions, freshly isolated type II cells from silica-treated animals produced more prostaglandin (PG) E2 than 6-keto-PGF1 alpha or thromboxane B2 (TxB2). Production of all three prostanoids increased with increasing cell size. The calcium ionophore A23187 stimulated a less than 2-fold increase in PGE2 and 6-keto-PGF1 alpha production in all groups of cells. In contrast, this calcium ionophore greatly enhanced TxB2 and leukotriene C4 (LTC4) production by normotrophic type II cells from both untreated and silica-treated animals. Incubation with exogenous AA suggested that the increased capability of the hypertrophic cells to synthesize PGE2 and TxB2 was due primarily to an increase in arachidonate availability. The hypertrophic type II cells also appear to have increased prostacyclin synthase activity. There were no differences in the catabolism of PGE2 between the normotrophic and the hypertrophic type II cells.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Surfactant protein C is expressed in alveolar type II cells but not in Clara cells of rat lung.

The expression of the surfactant-associated proteins in bronchiolar cells remains to be defined. We used in situ hybridization to identify sites of message expression of the surfactant-associated proteins A, B, and C (SP-A, SP-B, and SP-C) in adult and fetal rat lung. The expression of these messages by in situ hybridization was also compared with the localization of SP-A by immunocytochemistry. The localization of SP-A was used to identify type II cells and nonciliated bronchiolar epithelial (Clara) cells in these sections. The cRNA antisense probes for SP-A, SP-B, and SP-C appeared to hybridize over type II cells. Sense probes showed no localization or apparent specific hybridization. Messages for both SP-A and SP-B were also found in nonciliated bronchiolar epithelial (Clara) cells. However, no message for SP-C was observed in these cells. Clara cells from terminal to large bronchioles lacked detectable mRNA for SP-C. Expression of surfactant protein mRNAs was not detectable in type I cells, alveolar macrophages, interstitial cells, or vascular cells. Similarly, in fetal rat lung the messages for SP-A and SP-B but not SP-C were detected in bronchiolar cells. We conclude that rat Clara cells do not express SP-C mRNA, and thus SP-C can be regarded as a specific marker for rat type II cells.

Animals↗
PubMed1991

Idiopathic pulmonary fibrosis. Abnormalities in the bronchoalveolar lavage content of surfactant protein A.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease of the lung characterized by an inflammatory infiltrate, alveolar type II cell hypertrophy and hyperplasia, and ultimate parenchymal scarring. The phospholipid composition of the surface-active material recovered by bronchoalveolar lavage (BAL) is abnormal in this disease. In the present study we have extended the analysis of surfactant components in IPF to include the major surfactant-associated protein, surfactant protein A (SP-A). SP-A has been reported to be essential for the formation of tubular myelin, to facilitate the adsorption of phospholipid to the air/liquid interface, and to stimulate uptake and inhibit secretion of surfactant in vitro. The BAL of 25 normal volunteers and 42 patients with interstitial lung disease (ILD) was analyzed for surfactant protein A content by ELISA and for phospholipids. The changes in BAL components were correlated to histopathologic markers at open-lung biopsy, clinical status, and survival. The total phospholipid (PL) recovered at lavage was reduced in patients with IPF relative to normal volunteers (p less than 0.0005). In addition, the percentage of phosphatidyl-glycerol (% PG) was decreased in patients with IPF (p less than 0.0001), whereas the percentage of phosphatidylcholine that was saturated was not altered. The content of surfactant protein A in lavage was reduced, even when normalized for the total amount of surface-active material recovered (SP-A/PL) (p less than 0.007). The reduction in SP-A was not specific to IPF but also occurred in other interstitial lung diseases.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchoalveolar Lavage Fluid↗
PubMed1991

Temporal segregation of surfactant secretion and lamellar body biogenesis in primary cultures of rat alveolar type II cells.

Pulmonary alveolar type II cells synthesize and secrete the phospholipids of surfactant. However, type II cells isolated from adult rat lungs rapidly lose their characteristic morphology and differentiated functions (such as surfactant-specific phospholipid and protein biosynthesis) when maintained on tissue culture plastic. In this study, phospholipid secretion and its regulation by type II cells grown on tissue culture plastic were examined up to 8 days after isolation. Type II cells were preincubated with [3H]choline for varying 24-h periods during culture prior to examining phosphatidylcholine ([3H]PtdCho) secretion. Type II cells cultured for 4 days and incubated with [3H]choline 24 h before the secretion experiment failed to show significant basal and tetradecanoyl phorbol acetate (TPA, 100 nM)-stimulated [3H]PtdCho secretion (basal, 0.29 +/- 0.01%; TPA, 0.48 +/- 0.04%). In contrast, type II cells incubated with [3H]choline for the first 24 h during culture and then cultured for 3 more days showed significant [3H]PtdCho secretion (basal, 1.27 +/- 0.19%; TPA, 6.24 +/- 0.82%). Subcellular fractionation of type II cells revealed that [3H]choline was incorporated into phosphatidylcholines in a lamellar body-enriched fraction during the first 24 h of culture but that the assimilation of phosphatidylcholine into the lamellar body fraction progressively declined with increasing time in culture. Radiolabel incorporated into the lamellar body fraction labeled during the first 24 h of culture was detectable for up to 8 days in culture. The [3H]PtdCho incorporated into the lamellar body during the first 24 h of culture was lost gradually over 8 days, suggesting the continuous secretion or turnover of the lamellar bodies during culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Surface and tissue forces, surfactant protein A, and the phospholipid components of pulmonary surfactant in bleomycin-induced pulmonary fibrosis in the rat.

Administration of bleomycin to animals results in an alteration of the pressure-volume relationship of the lungs with an increased elastic recoil at any given volume. We sought to evaluate the relative importance of surface forces to elastic recoil by comparing the differences between the air and saline pressure-volume curves. The difference in elastic recoil between air- and saline-filled lungs was altered in bleomycin-treated rats when elastic recoil was compared at 35% of predicted TLC or at 80% of observed TLC. This pressure difference was present both during the early phase (Days 4 and 7) of the injury and acute inflammation as well as during the later phase (Days 14 to 28) when there was chronic inflammation and an elevation in the lung hydroxyproline content. The total amount of phospholipids recovered in lavage was decreased at Day 4 and increased more than 2.5-fold over saline-instilled control animals at Days 21 and 28. The percentage of phosphatidylglycerol was reduced and that of phosphatidylinositol increased. There was no consistent change in the percentage of phosphatidylcholine that was disaturated. The amount of surfactant protein A (SP-A) did not change during the course of the experiment and was not a useful independent marker of alveolar injury or changes in pulmonary compliance. The ratio of SP-A to total phospholipid decreased 14 to 28 days after instillation of bleomycin. These results support the hypothesis that individual components of surfactant are independently regulated and indicate that SP-A content in lavage is insensitive to lung injury and repair.

Animals↗
PubMed1990

Heparin-binding growth factors stimulate DNA synthesis in rat alveolar type II cells.

The proliferation of alveolar type II cells is important for repair of the alveolar epithelium after lung injury. We have previously reported that epidermal growth factor (EGF), insulin, cholera toxin, and endothelial cell growth supplement (ECGS) stimulate DNA synthesis of rat alveolar type II cells in culture. ECGS is a crude extract from bovine neural tissue that contains heparin-binding growth factors, and in this report we have compared the effect of ECGS to purified heparin-binding growth factors. ECGS stimulated [3H]thymidine incorporation into type II cells by 3-fold with half-maximal stimulation at 50 micrograms/ml. The purified acidic, class I heparin-binding growth factors, alpha-endothelial cell growth factor (-ECGF) and beta-ECGF stimulated type II cell DNA synthesis by 10-fold and 5-fold, respectively, with half-maximal stimulation at 40 ng/ml. Acidic fibroblast growth factor (FGFa) stimulated [3H]thymidine incorporation by 16-fold with half-maximal stimulation at 20 ng/ml, whereas basic FGF (FGFb) only stimulated type II cell DNA synthesis by 3-fold. Heparin potentiates the mitogenic effect of the acidic heparin-binding growth factors for both endothelial cells and fibroblasts but was found to inhibit FGFa- and FGFb-induced [3H]thymidine incorporation in type II cells by 80% with half-maximal inhibition occurring with 0.4 micrograms/ml and 1.3 micrograms/ml, respectively. When type II cells were cultured in the absence of serum, the heparin-binding growth factors had very little effect on [3H]thymidine incorporation. Only rat high density lipoprotein (HDL), but not insulin, EGF, or transferrin, was found to act synergistically with FGFa in stimulating [3H]thymidine incorporation in type II cells cultured in serum-free medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of a reconstituted basement membrane on expression of surfactant apoproteins in cultured adult rat alveolar type II cells.

Pulmonary surfactant, which is composed of phospholipids and three lung-specific apoproteins, is synthesized and secreted by alveolar type II cells. Previous work from this laboratory (Biochim. Biophys. Acta 1987; 931:143-156) has shown that cell-extracellular matrix interactions and cuboidal cell shape affect both the ultrastructural appearance and pattern of phospholipids synthesized by cultured rat type II cells. In the present study, we have examined the effects of cell-matrix interactions and cell shape on the ability of adult rat type II cells to express the surfactant apoproteins in culture. Isolated adult rat type II cells were cultured for 2, 4, and 8 days on either tissue culture plastic, on an extract of the Engelbreth-Holm-Swarm (EHS) tumor, or on laminin-coated plastic dishes. Expression of surfactant proteins A, B, and C (SP-A, SP-B, and SP-C) was evaluated by Northern analysis using specific rat cDNA probes for these mRNAs. SP-A content was determined by enzyme-linked immunosorbent assay using a polyclonal antibody raised against rat SP-A purified from lavage. Type II cells cultured on plastic dishes assumed an attenuated morphology soon after being placed in culture. Except for an occasional positive signal on day 2 of culture, these cells were uniformly negative for the presence of mRNA for SP-A, SP-B, or SP-C. Type II cells cultured on plastic did not contain SP-A. In contrast, type II cells cultured on EHS gels formed three-dimensional aggregates on the surface of the substratum; these aggregates were composed of polarized cells that had their apical surfaces directed inward. Type II cells cultured on this substratum showed a positive signal for mRNA for all three surfactant proteins; the abundance of these mRNAs, however, was significantly below that seen in freshly isolated type II cells. While the abundance of mRNA for SP-A and SP-B steadily increased with time in culture under these conditions, the abundance of SP-C mRNA decreased, suggesting that SP-C is regulated independently of SP-A and SP-B. These cultures were also positive for SP-A content, which increased with increasing time in culture. Type II cells cultured on laminin-coated dishes initially spread more slowly across the culture surface than cells on plastic, but were extremely attenuated by day 8 in culture. These cells contained neither SP-A, nor mRNA for any of the three surfactant proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Improved maintenance of adult rat alveolar type II cell differentiation in vitro: effect of serum-free, hormonally defined medium and a reconstituted basement membrane.

We have developed a serum-free, hormonally defined medium for maintenance of differentiation of adult type II cells cultured on Engelbreth-Holm-Swarm (EHS) tumor basement membrane gels. This defined medium consists of 1:1 (vol/vol) mixture of Ham's F12 and Dulbecco's modified Eagle's media supplemented with insulin, dibutyryl cyclic AMP, hydrocortisone, epidermal growth factor, selenium, and albumin/linoleic acid complex. Compared to cells cultured on EHS gels in serum-supplemented medium, type II cells cultured on EHS gels in this defined medium showed increased acetate incorporation into total lipids (10-fold) and an increase in the relative percentage of acetate incorporated into phosphatidylcholine (PC) (87.8 +/- 0.4% versus 78.5 +/- 1.0% [mean +/- SE]; P less than 0.01), saturated phosphatidylcholine (SPC) (61.4 +/- 0.5% versus 55.2 +/- 0.9%; P less than 0.01), and phosphatidylglycerol (PG) (5.3 +/- 0.3% versus 0.8 +/- 0.1%; P less than 0.01) and decreased acetate incorporation into neutral lipids (9.7 +/- 0.8% versus 62.6 +/- 1.9%; P less than 0.01). No response to this defined medium was seen when type II cells were cultured on tissue culture plastic. Type II cells cultured on EHS gels in serum-supplemented medium for 4 d had numerous neutral lipid droplets in their cytoplasm. In contrast, neutral lipid droplets were not commonly observed within the cytoplasm of the cells cultured in serum-free, hormonally defined medium on EHS gels. This morphologic finding was consistent with the result that cells cultured in serum-supplemented medium significantly increased the relative percentage of acetate incorporated into neutral lipids. These data indicate that adult type II cells cultured on a reconstituted basement membrane (EHS gels) can be maintained in synthetic culture medium without serum. These culture conditions permit the expression of a pattern of differentiated phospholipid biosynthesis and cell morphology more similar to normal type II cell differentiation.

Albumins↗
PubMed1990

Hypertrophic alveolar type II cells from silica-treated rats are committed to DNA synthesis in vitro.

Alveolar type II cell hyperplasia and hypertrophy are common reparative responses of the alveolar epithelium after silica-induced lung injury. We studied in vitro DNA synthesis in type II cells isolated after silica instillation in the rat to determine the proliferative potential of silica type II cells in primary culture and to correlate alveolar type II cell size with the level of in vitro DNA synthesis. To determine if the alveolar lining fluid is a source of growth factors that stimulate alveolar type II cell proliferation, we also examined the mitogenic effect of bronchoalveolar lavage fluid (BALF) from silica-treated rats on type II cells in primary culture. Alveolar type II cells were isolated from rats 1, 2, 3, and 4 wk after intratracheal silica instillation, cultured in DME supplemented with 10% fetal bovine serum, and labeled with [3H]thymidine from day 1 to day 3 in culture. DNA synthesis was determined by [3H]thymidine incorporation and autoradiographic labeling index. The level of thymidine incorporation increased progressively from 22.3 +/- 5.4 x 10(3) dpm/well 7 d after silica instillation to 34.4 +/- 5.0 x 10(3) dpm/well at 28 d. Type II cells isolated 14 d after silica instillation were separated into groups of increasing cell size by centrifugal elutriation. The plating efficiency and alveolar type II cell purity (greater than 88%) were the same in all groups of elutriated cells. The hypertrophic type II cells had a higher level of thymidine incorporation (22.0 +/- 2.8 x 10(3) dpm/well) than the normotrophic type II cells (11.1 +/- 0.7 x 10(3) dpm/well) [P less than 0.01]).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Human alveolar type II cells: stimulation of DNA synthesis by insulin and endothelial cell growth supplement.

Proliferation of type II cells is important for the recovery of the alveolar epithelium after acute lung injury. However, the factors that regulate the proliferation of human type II cells are unknown. Human alveolar type II cells were isolated from resected lung by dissociation with porcine pancreatic elastase and crystalline trypsin and purified by density-gradient centrifugation and serial differential adherence. The purity of the type II cells in the final adherent preparation was 84.4 +/- 1.1% type II cells by alkaline phosphatase and 87.7 +/- 2.8% by cytokeratin (n = 7). The medium MCDB-151 with 0.4% fetal bovine serum (FBS) was used to demonstrate the stimulatory effect of individual growth factors. Under these conditions, thymidine incorporation was stimulated by insulin, epidermal growth factor, endothelial cell growth supplement (ECGS), and acidic and basic fibroblast growth factors. Cholera toxin did not stimulate thymidine incorporation. The most effective stimulation was by the combination of insulin and ECGS. The incorporation of bromodeoxyuridine was used to identify the proportion of cells that were active in DNA synthesis. Insulin and ECGS increased the percentage of cells that incorporated bromodeoxyuridine from 8.5 +/- 1.3% to 21.3 +/- 2.4% (n = 6). Mitotic figures were seen in smears prepared from cultures incubated with insulin and ECGS. This observation was confirmed by electron microscopy, which demonstrated type II cells in metaphase. Increasing the concentration of FBS or human serum in the culture medium to 10% decreased the stimulatory effect of insulin and ECGS.(ABSTRACT TRUNCATED AT 250 WORDS)

Bromodeoxyuridine↗
PubMed1989

Nucleotide and deduced amino acid sequence of the hydrophobic surfactant protein SP-C from rat: expression in alveolar type II cells and homology with SP-C from other species.

Pulmonary surfactant lowers surface tension in the lung. Its deficiency leads to the severe physiologic abnormalities seen in the respiratory distress syndrome. The hydrophobic surfactant proteins, SP-B and SP-C, appear to be especially important in the surface-spreading characteristics of pulmonary surfactant. We report the nucleotide sequence of cDNA clones for rat SP-C and compare the deduced amino acid sequence for SP-C from several species. A highly conserved domain exists within the confines of mature human SP-C. An Eisenberg plot of this region predicts a membrane-associated helix. We also demonstrate by Northern analysis the tissue-specific expression of SP-C. A comparison of signal strength between total lung RNA and RNA derived from isolated type II cells supports the idea that most SP-C messenger RNA in total lung can be accounted for by that present in alveolar type II cells.

Amino Acid Sequence↗
PubMed1989

cDNA and deduced amino acid sequence for the rat hydrophobic pulmonary surfactant-associated protein, SP-B.

Pulmonary surfactant prevents collapse of lung alveoli by lowering surface tension at the air/liquid interface. The hydrophobic surfactant associated proteins SP-B and SP-C have been shown to be important in surfactant function and metabolism. A cDNA clone for rat SP-B was isolated and sequenced. Northern analysis showed mRNA for SP-B was present in whole lung and was greatly enriched in alveolar type II cells, but was not present in brain, kidney, spleen or liver. A full length transcript of the rat SP-B cDNA clone consists of 1536 bases and encodes an open reading frame of 376 amino acids. The predicted molecular mass of the primary translation product is 42 kDa and the predicted molecular mass of the mature protein is 8 kDa. Extensive homology exists between the rat sequence for SP-B and those reported for human and canine SP-B. The position of 25 cysteine residues has been extremely well preserved across all three species. An N-linked glycosylation site in the COOH region has been conserved across all three species. A search of the NIH database revealed homology between rat SP-B and the active site for the mouse contrapsin serum proteinase inhibitor.

Amino Acid Sequence↗
PubMed1989

The syndrome of inappropriate antidiuretic hormone secretion and its effect on blood indices following spinal fusion.

Red blood cell indices in four adolescent and preadolescent patients with documented inappropriate antidiuretic hormone secretion (SIADH) following spinal fusion were examined for evidence of dilution. The blood indices in these preoperative patients demonstrated evidence of dilution on both the intracellular and extracellular levels. The major factors causing these dilutional effects were elevated ADH, intravenous fluid overloading, and mobilization of "third space" fluids. It appears that extracellular dilution secondary to these factors results in spuriously low blood indices (namely, hemoglobin, hematocrit, and red blood cells) during the postoperative period. These findings suggest that an awareness of SIADH and avoiding intravenous fluid overloads by accurately managing intraoperative and postoperative fluids will decrease the dilutional effects observed on blood indices and perhaps save patients from unwarranted transfusions.

Adolescent↗