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Biomedical subjects

D Lagunoff

Publications and source records attributed to D Lagunoff.

At least 19 recordsLinked to original sources
PubMed1991

Rat mast cell tryptase.

Rat mast cell tryptase is located largely if not totally in the cell's secretory granules. When the active site reagent [3H]diisopropyl fluorophosphate was used to label tryptase and chymase simultaneously, the ratio of tryptase:chymase active sites was determined to be 0.05. In comparison to chymase and tryptase in other species and chymase in the rat, rat tryptase is poorly bound to the granule matrix as evidenced by (1) its release parallel to histamine on induction of secretion and (2) its appearance in the supernatant when isolated granules were stripped of their membranes with hypotonic medium. Tryptase on release from the granule is moderately stable at a pH of 5.0 but unstable at pH 7.5, the pH that the enzyme encounters on secretion from the cell. These several properties indicate that the role of rat mast cell tryptase extracellularly is likely to differ greatly from that of chymase.

Animals↗
PubMed1991

Regulation of permeabilized endothelial cell retraction by myosin phosphorylation.

Permeabilized endothelial cell monolayers retracted on exposure to ATP and Ca2+. ADP, inosine triphosphate (ITP), GTP, adenosine 5'-(gamma-thio)triphosphate (ATP-gamma S), and 5'-adenylylimidodiphosphate failed to support retraction. However, ATP gamma S, a substrate for myosin light-chain kinase (MLCK) but not myosin adenosinetriphosphatase (ATPase), combined with ITP, a substrate for myosin ATPase but not MLCK, supported retraction. Two MLCK pseudosubstrate peptides, M5 and SM-1, inhibited endothelial cell retraction equally and more effectively than myosin kinase-inhibitory peptide with a sequence based on the phosphorylated site of myosin light chain. M5 was shown to inhibit thiophosphorylation of endothelial cell myosin light chains. Endothelial cells incubated with exogenous unregulated kinase in the presence of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetra-acetic acid retracted on addition of ATP. This retraction was accompanied by thiophosphorylation of the 19 kDa myosin light chains in the presence of ATP gamma 35S. The N-ethylmaleimide-modified subfragment 1 of myosin heads, a specific inhibitor of actin-myosin interaction, prevented retraction. These data add support to the proposal of a central role for MLCK activation of myosin in endothelial retraction.

Adenosine Triphosphate↗
PubMed1991

Administration of chronic intravenous platelet-activating factor induces pulmonary arterial atrophy and hypertension in rabbits.

Platelet-activating factor (PAF), a lipid mediator of inflammation, was given by continuous intravenous infusion to rabbits for 2, 4, and 8 weeks, and morphologic and hemodynamic findings were correlated. Pulmonary arterial pressure (PAP), cardiac output, and right atrial pressure were measured, and total pulmonary resistance was calculated. In cross-sections of intraparenchymal pulmonary arteries, internal elastic lamina circumference and intimal and medial areas were measured. The ratio of the weight of the right ventricle to the weight of the left ventricle plus septum, and alveolar/artery ratios were also obtained. In bronchoalveolar lavage fluid, total and differential cell counts were determined. After 2 weeks of PAF treatment, PAP rose by 4 mm Hg. The increase in PAP became significant by 4 weeks and remained so at 8 weeks of treatment. Total pulmonary resistance nearly doubled by 2 weeks and continued to be elevated throughout 8 weeks of PAF treatment. Cardiac output fell significantly to 0.26 liters/minute at 2 weeks of PAF treatment and remained low at 4 weeks. By 8 weeks of treatment, it normalized. The significant rise in total pulmonary resistance at 2 and 4 weeks correlated with the rise in PAP and the fall in cardiac output. The alveolar/artery ratio was increased at 2 weeks of treatment and progressively increased at 4 and 8 weeks, reaching statistical significance at 8 weeks. In intra-acinar arteries, after 2 weeks of treatment, there was a reduction in total cross-sectional area (within the external elastic lamina), medial area, and internal elastic lamina circumference measured by computerized image analysis of 5-microns thick Verhoeff Van Gieson-stained sections. Changes in total area, medial area, and internal elastic lamina circumference persisted after 4 and 8 weeks of treatment. In preacinar arteries, similar changes occurred that were significant only after 8 weeks of treatment. Other findings apparent at 2 weeks of treatment included right ventricular hypertrophy and a marked decline in the number of macrophages and lymphocytes recovered from bronchoalveolar lavage fluid. We conclude that chronic intravenous infusion of PAF in rabbits induces remodeling of pulmonary arteries, specifically reduction of the internal elastic lamina, with consequent narrowing of arterial lumens producing increased pulmonary vascular resistance and pulmonary hypertension. We attribute the increase in alveolar/artery without evident vessel obliteration, to a shortening of arterial length, which is of insufficient magnitude to overcome the effect of vessel narrowing on vascular resistance.

Animals↗
PubMed1990

Involvement of myosin light-chain kinase in endothelial cell retraction.

Permeabilized bovine pulmonary artery endothelial cell monolayers were used to investigate the mechanism of endothelial cell retraction. Postconfluent endothelial cells permeabilized with saponin retracted upon exposure to ATP and Ca2+. Retraction was accompanied by thiophosphorylation of 19,000-Da myosin light chains when adenosine 5'-[gamma-[35S]thio]triphosphate was included in the medium. Both retraction and thiophosphorylation of myosin light chains exhibited a graded quantitative dependence on Ca2+. When permeabilized monolayers were extracted in buffer D containing 100 mM KCl and 30 mM MgCl2 for 30 min, the cells failed to retract upon exposure to ATP and Ca2+, and no thiophosphorylation of myosin light chains occurred. The ability both to retract and to thiophosphorylate myosin light chains was restored by the addition to the permeabilized, extracted cells of myosin light-chain kinase and calmodulin together but not by either alone. These studies indicate that endothelial cell retraction, as does smooth muscle contraction, depends on myosin light-chain kinase phosphorylation of myosin light chains.

Actins↗
PubMed1990

A rabbit model of pulmonary hypertension induced by the synthetic platelet-activating factor acetylglyceryl ether phosphorylcholine.

Development of effective treatment for human pulmonary hypertension (PHT) has been hampered by an incomplete understanding of its pathogenesis. We present a rabbit model of PHT based on platelet-activating factor (PAF), a potent phospholipid autacoid synthesized by a variety of mammalian cells. PAF was intravenously infused into rabbits for 4 wk. After the infusion, rabbits underwent pulmonary arterial catheterization for hemodynamic evaluation, and lung tissue was morphometrically analyzed for changes in cross-sectional areas of intima and media, and alteration in number of small pulmonary arteries. The heart was evaluated by the method of Fulton for right ventricular hypertrophy. Mean pulmonary arterial pressure was 20 +/- 2 mm Hg in PAF-treated rabbits compared with 12 +/- 1 mm Hg in vehicle-treated control rabbits. PAF induced a trend toward loss of small muscular pulmonary arteries, measuring 50 to 200 microns in diameter, and right ventricular hypertrophy. There was a decrease in circumference of the internal elastic lamina in vessels accompanying alveolar ducts and in alveolar walls, and a relative increase in the intimal cross-sectional area of these vessels. These lesions were associated with a trend toward medial hypertrophy. No increase in lung water was found. Pressure changes occurred in the absence of alterations in hematocrit and arterial partial pressure of oxygen. We conclude that chronic intravenous infusion of PAF, a naturally synthesized substance, into rabbits provides a potentially useful model for the study of vascular changes associated with PHT.

Animals↗
PubMed1989

Protein malnutrition: effect on rat peritoneal mast cell number, histamine content, and IgE receptors.

To examine the effects of protein malnutrition on mast cells, rats were fed a protein-deficient diet (0.5% protein ad libitum) or normal diet (27% protein ad libitum or pair fed) for 16, 21, 27, or 57 d. Male rats in the different groups showed no significant differences in mast cell number or histamine content per mast cell. IgE binding sites as measured by flow cytometry were decreased in rats on the deficient diet. Even after stripping receptors of endogenous IgE and then labeling with fluorescent IgE, the difference remained, thus confirming the lower number of mast cell IgE receptors in rats maintained on the protein-deficient diet.

Animals↗
PubMed1986

Antagonism of the final common pathway of mast cell histamine secretion by arylalkylamines.

The antagonism of histamine secretion from rat peritoneal mast cells by a range of drugs (e.g., antihistamines, local anesthetics, tranquilizers, antidepressants, adrenergics and antiadrenergics) and arylalkylamines was studied. Simple arylalkylamines, those without quaternary ammonium, phenolic or anionic groups, uniformly inhibited histamine secretion induced via three major secretory pathways of mast cells (compound 48/80, A23187 and concanavalin A). That is, each simple arylalkylamine nonselectively inhibited all three secretagogues at about the same concentration (avg. range = 2.2). This nonselective inhibition was rapid in onset (seconds), readily reversible by washing and not related to a decrease in ATP. It is likely that these agents act nonspecifically at a step in the final common pathway in the cell membrane, possibly to inhibit fusion of the secretory granules with the plasma membrane. Other, more complex arylalkylamines were selective in their antagonism of histamine secretion. Quaternary arylalkylammonium compounds selectively antagonized polyamine secretagogues (48/80 and polymyxin B), whereas arylalkylamines, with other hydrophilic groups, selectively inhibited one or another of the secretory pathways. These complex arylalkylamines must act before the final common pathway because of their selective inhibition. At higher concentrations most of the arylalkylamines caused disruption of the mast cells and liberated histamine.

Adenosine Triphosphate↗
PubMed1979

Inhibition of mast cell histamine secretion by N-substituteed derivatives of phosphatidylserine.

The structural basis for the highly specific action of phosphatidylserine in enhancing mast cell histamine secretion induced by concanavalin A was investigated by studying the activities of three N-substituted derivatives: N-acetyl phosphatidylserine, N-1-dimethylaminonaphthalene-5-sulfonly phosphatidylserine, and N-4-nitrobenzo-2-oxa-1,3-diazole phosphatidylserine. None of the derivatives was capable of activating concanavalin A-induced histamine secretion at concentrations two to three times that required for maximal activation by phosphatidylserine. Instead, the derivatives were found to inhibit the secretory response of mast cells to the calcium ionophore A23187 as well as to concanavalin A. The inhibition was noncytotoxic, partially reversible by washing, and associated with binding of N-substituted phosphatidylserine to the mast cell.

Animals↗
PubMed1978

Neurological manifestations of Fabry disease in female carriers.

A family is described in which a 33-year-old man has classic X-linked recessive Fabry disease. His 2 sisters were discovered to be heterozygous carriers of the Fabry gene and to have both episodic and permanent neurological deficits including vertigo, tinnitus, long tract motor signs, and bladder incontinence. The most concise explanation for these findings is that the sisters manifest central nervous system complications of the Fabry carrier state. This family provides additional evidence that female carriers of rare X-linked recessive disorders may exhibit serious consequences of the disease, presumably related to tissue variability in expression of mutant enzyme activity.

Adult↗
PubMed1978

Interaction of phosphatidylserine with mast cells.

Phosphatidylserine (PtdSer) potentiates histamine secretion from mast cells exposed to concanavalin A and Ca2+. In order to identify the form of PtdSer that is responsible for its effect on mast cell secretion, PtdSer containing a tritium-labeled serine moiety (3H-PtdSer) was synthesized from egg yolk phosphatidylcholine. The critical micelle concentration (CMC) of 3H-PtdSer and the binding isotherm for 3H-PtdSer interaction with mast cells were determined. The midpoints of the binding isotherm and the dose-response curve for potentiation of secretion coincide and are 2 orders of magnitude greater than the CMC. The shape of the binding curve is explicable either in terms of simple binding of preformed PtdSer micelles or of cooperative binding of monomeric PtdSer in which the number of molecules cooperatively associating with a mast cell binding site is equal to the number of monomers in a PtdSer micelle. In either case, at equilibrium, PtdSer micelles are bound to the mast cells. The number of PtdSer molecules bound to a single mast cell at equilibrium was estimated to be 3.7 X 10(9).

Animals↗
PubMed1978

A major serine protease in rat skeletal muscle: evidence for its mast cell origin.

The physical, chemical, and immunologic properties of a protease from rat skeletal muscle, proposed to function in the degradation of certain intracellular enzymes, are identical to those of a chymotrypsin-like serine protease isolated from peritoneal mast cells. The results of polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and 8 M urea indicate that the two rat proteases have identical mobilities corresponding to a molecular weight of 26,000. The relative amino acid compositions of the proteases are nearly identical. Immunodiffusion tests for crossreaction between the muscle protease and antisera directed toward mast cell protease indicate that the former is immunologically identical to mast cell protease. The first 35 amino-terminal residues of the two enzymes are identical and indicate homology of these proteins to other mammalian serine proteases. The sequence analysis of the protease from muscle was extended for an additional 16 positions, and comparison of this amino-terminal sequence with that of a similar enzyme from small intestine showed approximately 75% sequence identity. In contrast, only 40% of the residues in this region of bovine chymotrypsin A were found at corresponding loci in rat muscle protease. It is concluded that the protease from muscle or mast cells is closely related to the enzyme from small intestine which recently was localized in the "atypical" mast cells of gut mucosa [Woodbury, R. G., Gruzenski, G. M. & Lagunoff, D. (1978) Proc. Natl. Acad. Sci. USA 75, 2785-2789].

Amino Acid Sequence↗
PubMed1978

Linear arrays of intramembranous particles in pulmonary tubular myelin.

Freeze-fracture preparations of tubular myelin in edematous rat lungs reveal the presence of linear arrays of intramembranous particles. The lines of particles are approximately 50 nm apart and appear to correspond to the intersections of sheets of bilayer membranes. Particles are not seen in lamellar bodies but become evident first in membranes transitional between lamellar bodies and tubular myelin. It is proposed that the particles represent a hydrophobic protein that plays a significant role in the organization of tubular myelin.

Animals↗
PubMed1978

Immunofluorescent localization of a serine protease in rat small intestine.

An intracellular serine protease, which is believed to initiate the degradation of several intracellular pyridoxal phosphate-dependent enzymes, was localized by immunofluorescence in atypical mast cells of the lamina propria and in intraepithelial cells of the rat small intestine. Some mucus-secreting goblet cells also contained the protease antigen. Atypical mast cells containing the enzyme were present in large numbers beneath the epithelium of bronchioles. All atypical mast cells also contained low levels of the chymotrypsin-like protease of normal mast cells. Both enzymes were consistently present in normal connective tissue mast cells. Amino acid content, molecular weight, and lack of immunologic crossreactivity indicate that the two enzymes are similar but not identical. The cell-specific localization of the intestinal serine protease makes it unlikely that the enzyme has any general role in the degradation of pyridoxal phosphate-dependent enzymes. The function of the enzyme in mast cells, atypical mast cells, and intestinal goblet cells is not known.

Animals↗