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Biomedical subjects

E P Lewis

Publications and source records attributed to E P Lewis.

At least 19 recordsLinked to original sources
PubMed1998

Lung matrix deposition of normal and alkylated plasma fibronectin: response to postsurgical sepsis.

Plasma fibronectin (Fn) can both enhance phagocytic clearance of microparticulate debris by macrophages as well as incorporate it into the lung extracellular matrix (ECM). The goal of this study was to document that N-ethylmaleimide (NEM)-treated human plasma Fn (HFn) would lose its ability to incorporate into the lung ECM in vivo even though it would retain its ability to stimulate test particle phagocytosis and bind to fibrin. Using dual-label immunofluorescence, we compared the lung deposition of purified normal HFn and NEM-alkylated HFn (NEM-HFn) after their intravenous injection into postoperative nonbacteremic and bacteremic sheep in relationship to the localization of endogenous sheep Fn. Two days after a sterile surgical thoracotomy, sheep were infused with either 5 x 10(8) Pseudomonas aeruginosa (postsurgical bacteremic model) or the diluent (nonbacteremic model). They also received a bolus 100-mg injection (5 min) of either HFn or NEM-HFn. Analysis of serial lung biopsies harvested at 2-h intervals demonstrated little deposition of NEM-HFn compared with HFn in the lung interstitial matrix of postoperative nonbacteremic sheep. In contrast, enhanced deposition of both HFn and NEM-HFn was observed in the lungs of postoperative bacteremic sheep. However, in the lungs of bacteremic sheep, HFn displayed a diffuse fibrillar deposition pattern in the lung characteristic of ECM incorporation, whereas the enhanced NEM-HFn deposition, especially in the interstitial ECM region of the lung, was primarily focal and punctate, with very little fibrillar incorporation. Immunofluorescent analysis with antibodies specific to fibrinogen, Fn, and lung macrophage surface antigens coupled with immunoperoxidase staining for HFn antigen revealed that the punctate fluorescence pattern was due to both the binding of HFn to fibrin and its colocalization with inflammatory cells. Thus treatment of plasma Fn with low concentrations of NEM will limit its normal in vivo fibrillar incorporation into the interstitial ECM region of the lung.

Alkylation↗
PubMed1994

Delayed elevation of ED1-cellular fibronectin in plasma following postsurgical bacteremia.

Fibronectin (Fn) exists in both a soluble form in plasma and lymph as well as an insoluble form in the extracellular matrix. Matrix-localized cellular fibronectin (cFn) contains extra domains (ED1 and/or ED2) not found in plasma Fn (pFn). Very little (< 1-2%) ED1-containing cFn exists in normal blood, and its rapid release into plasma and/or lymph is believed to reflect acute vascular injury. We used a polyclonal antibody to sheep pFn and a monoclonal antibody to ED1 domain of cFn to measure both pFn and ED1-cFn in relationship to lung lymph flow (QL), lung lymph-to-plasma (L/P) total protein concentration ratio, and lung protein clearance (LPC). Unanesthetized sheep (n = 7) were injected intravenously with Pseudomonas aeruginosa (5 x 10(8)) at both 2 and 7 days following surgical preparation of a lung lymph fistula. After both bacterial challenges, we observed an early increase in QL and a small decline in the L/P ratio (0-2 h), reflecting increased fluid filtration in the presence of an intact vascular barrier. This was followed by a further increase (P < 0.05) in QL; an elevation in the L/P ratio; and a marked (P < 0.05) increase in LPC over 3-6 h, indicative of an increase in lung endothelial protein permeability. Before the first bacterial infusion, ED1-cFn in plasma was 9.97 micrograms/ml or approximately 2% of the total Fn antigen in plasma; whereas ED1-cFn in lung lymph was 6-8% of total lymph Fn.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Release of ED1 fibronectin from matrix of perfused lungs after vascular injury is independent of protein synthesis.

Fibronectin (Fn) is an adhesive protein found in the plasma and extracellular tissue matrix. Locally synthesized tissue or cellular Fn (cFn) has extra domains (ED1 and ED2) not present in liver synthesized plasma Fn (pFn). In the lung, Fn is found in the endothelial and epithelial basement membranes, as well as in the interstitial matrix. Utilizing murine monoclonal antibodies to ED1 of cFn, we studied the release of total Fn as well as ED1-Fn into the plasma-free perfusate of the isolated perfused rabbit lung in relation to changes in lung weight due to fluid accumulation after oxidant (H2O2) challenge. Both parameters were also studied after addition of cycloheximide (20 micrograms/ml perfusate) to the perfusion medium to inhibit lung protein synthesis. After continuous H2O2 challenge (11 nmol.ml buffer-1.min-1), there was a 2.25 +/- 0.62 g increase in lung weight over 60 min. Measurement of 125I-labeled albumin clearance at 20 min after the start of H2O2 infusion confirmed an increase in lung endothelial protein permeability after H2O2 treatment. Fn antigen was released into the perfusate as early as 15 min after oxidant challenge. By 60 min, total perfusate Fn increased in H2O2-treated lungs (n = 6) to 2.10 +/- 0.48 micrograms/ml compared with only 0.35 +/- 0.09 micrograms/ml in normal control lungs (n = 5). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of nonreduced samples revealed that the Fn released consisted of primarily intact (440 kDa) Fn as well as Fn fragments. A rapid release of ED1-Fn paralleled the increased release of total Fn.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Pulmonary and peripheral lymph protein clearance during bacteremia after surgery.

An increase in pulmonary transvascular protein clearance is seen in sheep following postoperative bacteremia. We evaluated whether this increased protein clearance is specific for the lung by comparing in sheep the effect of postoperative bacteremia on both pulmonary and prefemoral lymph protein clearance. Fibronectin, implicated as a factor influencing vascular permeability, was also measured. After intravenous infusion of a sublethal dose of 5 x 10(8) live Pseudomonas aeruginosa (n = 10), pulmonary lymph flow (QL) increased 146% (P less than 0.01), and the lung lymph-to-plasma (L/P) total protein concentration ratio increased 21% (P less than 0.05). This resulted in a 208% elevation (P less than 0.01) in lung protein clearance (LPC = QL x L/P). In contrast, peripheral lymph flow and peripheral protein clearance were not altered. After intravenous infusion of a lethal dose of 5 x 10(9) live Pseudomonas (n = 7), QL rose 243-348% (P less than 0.025), whereas the lung L/P remained at base line, resulting in a 240-358% increase in LPC (P less than 0.025). Again, peripheral lymph flow and protein clearance did not increase. Plasma fibronectin declined slightly after low-dose bacterial challenge but decreased (P less than 0.001) 40% by 4-5 h after high-dose bacterial challenge. After both low- and high-dose bacterial challenge, fibronectin in pulmonary lymph increased (P less than 0.05) relative to total protein. In contrast, no change in peripheral lymph fibronectin was seen. Thus, while postoperative bacteremia increased lung protein clearance, it did not increase peripheral protein clearance, suggesting specificity with regard to the microvascular response to bacteremia.

Animals↗
PubMed1985

Examination of a series of 8-[3-[bis(4-fluorophenyl)amino]propyl]-1-aryl-1,3,8- triazaspiro[4.5]decan-4-ones as potential antipsychotic agents.

8-[3-[Bis(4-fluorophenyl)amino]propyl]-1-phenyl-1,3,8- triazaspiro[4.5]decan-4-one (3) and related compounds have been shown to have antipsychotic profiles in biochemical and behavioral pharmacological test models. The dose of 3 necessary to produce catalepsy in rats is much greater than that required for activity in behavioral tests predictive of antipsychotic efficacy, for example the suppression of high base line medial forebrain bundle self-stimulation in rats. This suggests that 3 would have a reduced propensity for neurological side effects. The effects of substitution on the 1-phenyl moiety and on the N-3 nitrogen atom of the triazaspirodecanone portion of 3 were examined. Results from this study suggest that behavioral activity is sensitive to substituents on the 1-phenyl moiety while substituents on the N-3 nitrogen are more generally tolerated. In both rats and squirrel monkeys compound 3 was found to have a similar separation between doses inhibiting Sidman avoidance activity and those causing catalepsy. However, in an extrapyramidal side effect (EPS) test model using haloperidol-sensitized cebus monkeys, 3 elicited signs of EPS at doses approximating those previously determined to be efficacious.

Animals↗
PubMed1985

1-[3-(Diarylamino)propyl]piperidines and related compounds, potential antipsychotic agents with low cataleptogenic profiles.

On the basis of a structural model of the postsynaptic dopaminergic antagonist pharmacophore, a series of 1-[3-(diarylamino)propyl]piperidines and related compounds was synthesized and evaluated for potential antipsychotic activity. For a rapid measure of activity, the target compounds were initially screened in vitro for inhibition of [3H]haloperidol binding and in vivo in a test of locomotor activity. Behavioral efficacy of compounds identified from the initial screens was more accurately measured in rats by using a suppression of high base-line medial forebrain bundle self-stimulation test model. The propensity of these compounds for causing extrapyramidal side effects was evaluated by using a rat catalepsy method. On the basis of these test models, we have shown that the methine carbon of the 1-(4,4-diarylbutyl)piperidines can be advantageously replaced with a nitrogen atom. The 1-[3-(diarylamino)propyl]piperidines were less cataleptic than the corresponding 1-(4,4-diarylbutyl)piperidines. The compounds with the widest separation between efficacious dose and cataleptic dose are 8-[3-[bis(4-fluorophenyl)amino]propyl]-1-phenyl-1,3,8-triazaspiro [4. 5]decan-4-one (6), 1-[1-[3-[bis(4-fluorophenyl)amino]propyl]-4-piperidinyl]-1,3-dihydro- 2H-benzimidazol-2-one (11), 1-[1-[3-[bis(4-fluorophenyl)amino]propyl]-1,2,3,6-tetrahydro-4- pyridinyl]-1,3-dihydro-2H-benzimidazol-2-one (22), and 1-[3-[bis(4-fluorophenyl)amino]propyl]-4-(2-methoxyphenyl)piperazine (26).

Animals↗
PubMed1985

Lung vascular injury with protease infusion. Relationship to plasma fibronectin.

Fibronectin exists in a soluble form in plasma and in an insoluble form in tissues. Plasma fibronectin can modulate phagocytic function as well as incorporate into the tissue matrix where it is believed to influence microvascular integrity and tissue repair. The temporal alterations in plasma and lung lymph fibronectin were studied in relation to increased pulmonary vascular permeability induced by protease infusion. The acute sheep lung lymph fistula model was used. A 39% decrease in plasma fibronectin (control = 421 +/- 67 micrograms/ml) was observed 2.5 hours (255 +/- 43 micrograms/ml) after protease infusion. There was an elevation of lymph fibronectin early after protease infusion, followed by a progressive decline. Concomitant with the decrease in plasma fibronectin, an increase in lymph flow (QL) of greater than 200% (from a control of 6.7 +/- 1.0 ml/hr to 13.9 +/- 1.4 ml/hr) was observed within 2.5 hours. Also, there was a sustained elevation in the total protein lymph/plasma concentration (L/P) ratio, which was maximal at 2.5 hours. The transvascular protein clearance (TVPC = QL X L/P) was 4.5 +/- 0.7 ml/hr at the control period and 13.1 +/- 2.0 ml/hr by 2.5 hours. This was indicative of increased flux of protein-rich fluid across the pulmonary endothelial barrier. Lung vascular permeability stabilized after 2.5 hours as manifested by a slowly declining L/P ratio. Thus, plasma fibronectin deficiency may contribute to the etiology of increased lung vascular permeability with protease infusion. Since the progressive decline in plasma fibronectin was not reflected in a proportional increase in lymph fibronectin, plasma fibronectin may have sequestered in tissues such as the lung, or perhaps in reticuloendothelial cells during the injury phase. Whether the progressive decrease in plasma fibronectin reflects its incorporation into the endothelial barrier matrix where it may mediate stabilization of the pulmonary microvascular barrier remains to be determined.

Animals↗
PubMed1984

Clearance from the vascular compartment of endogenously labelled plasma fibronectin.

Plasma fibronectin is a large molecular weight glycoprotein which may have both opsonic and structural adhesive roles. Fibronectin deficiency has been documented in patients especially early after trauma or burn as well as during sepsis following injury. In this study, the disappearance of fibronectin from the blood was studied in rats utilizing plasma fibronectin metabolically labelled with 75Se-selenomethionine. After injection of 75Se-selenomethionine, the maximum specific activity of endogenously labelled plasma fibronectin, the observed at 4 hours. Thereafter, it declined in a non-monoexponential fashion in association with depletion of the precursor. Labelled 75Se fibronectin was purified from donor rat plasma by gelatin-sepharose affinity chromatography. It retained its electrophoretic mobility, gelatin adherence, and opsonic activity similar to that of unlabelled plasma fibronectin. Following intravenous injection of 75Se plasma fibronectin, its disappearance from plasma manifested two phases. The first was an initial fast disappearance of a small amount of fibronectin, reflecting distribution between plasma and interstitial compartments. The second was a slower disappearance phase with a half-time (T 1/2) of at least 15 hours. Infusion of gelatin-coated particles, which are rapidly cleared by RE cells in the liver and spleen, enhanced the disappearance of 75Se fibronectin from the plasma. These data suggest that the normal rate of fibronectin disappearance from the vascular space is quite fast. Utilization of this experimental approach may provide valuable data on fibronectin kinetics as influenced by trauma and burn.

Animals↗
PubMed1983

Actin-induced reticuloendothelial phagocytic depression as mediated by its interaction with fibronectin.

Circulating fibronectin, also known as opsonic alpha 2 surface binding glycoprotein or cold-insoluble globulin, modulates phagocytosis of tissue debris, fibrin microaggregates, and gelatin-coated colloids by the reticuloendothelial (RE) system. Opsonically active fibronectin has an actin binding site and a demonstrated in vitro affinity for actin. Since actin potentially released into blood and tissue fluids following tissue injury could complex with fibronectin, the present study evaluated the effect of actin on plasma opsonic activity and Kupffer cell phagocytosis. Intravenous injection of actin did not acutely decrease plasma immunoreactive fibronectin levels although fibronectin levels increased at 6, 12, and 24 hr postinjection. However, intravenous actin injection did depress RE phagocytic activity in vivo as measured by decreased blood clearance of test colloid and impaired hepatic uptake of colloid particles as well as retention of the particles in the circulation. In vitro, preincubation of plasma with actin depressed the opsonic activity of plasma with respect to its ability to support phagocytosis, but such treatment of plasma did not alter the detection of fibronectin by immunoassay. Utilizing purified fibronectin with demonstrated opsonic activity, it was also observed that actin interaction with fibronectin would block its biological ability to enhance phagocytosis. This effect appeared to be mediated at the humoral level, since no direct depressant effect of actin on Kupffer cell function was observed. Thus, actin, if released into the blood following injury, may contribute to bioassayable opsonic fibronectin deficiency and phagocytic dysfunction, but this disturbance would remain undetectable by immunoassay of fibronectin levels.

Actins↗
PubMed1983

Kinetics of endogenously labeled plasma fibronectin: incorporation into tissues.

Fibronectin exists in a soluble form in plasma and lymph as well as in a relatively insoluble form in tissues. The disappearance of endogenously labeled fibronectin from plasma and its subsequent extravascular localization was studied over a 38-h period in normal rats (350-400 g) utilizing plasma fibronectin labeled in vivo with 75Se-selenomethionine. For comparative analysis, 125I-albumin was utilized in these dual isotopic experiments. After the simultaneous injection of 75Se plasma fibronectin (20 nCi) and 125I-albumin (2 microCi), all measured tissues demonstrated accumulation of both radiolabeled proteins in extravascular sites. Plasma fibronectin demonstrated a rather specific and high affinity for liver and spleen, which are enriched with reticuloendothelial cells. Albumin manifested the expected washout from extravascular sites, whereas fibronectin primarily displayed retention in tissues. The plasma disappearance of 75Se-labeled fibronectin was well described by two exponentials: an early phase with a half time of 0.52 h and a later phase with a half time of 21 h. To account for tissue retention of labeled fibronectin, a two-compartment kinetics model was required that included loss from the extravascular exchangeable compartment. Analysis of the disappearance kinetics and fibronectin distribution allowed estimation of the fractional turnover rate, pool size, and mean residence time. Accordingly the total rate of loss for plasma fibronectin was 0.51-0.54 mg/h. The calculated pool size of the soluble form of fibronectin was 15.5-16.3 mg. The mean residence time for exchangeable fibronectin was 29.6-29.9 h. These findings suggest that plasma fibronectin can be incorporated within the insoluble pool of fibronectin in tissues.

Animals↗