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J Chacko

Publications and source records attributed to J Chacko.

33 records · Page 2Linked to original sources
PubMed1996

Interaction of the fibrinolytic receptor, annexin II, with the endothelial cell surface. Essential role of endonexin repeat 2.

Endothelial cells express a cell surface co-receptor for plasminogen and tissue plasminogen activator (t-PA) which we recently identified as annexin II (Hajjar, K. A., Jacovina, A. T., and Chacko, J. (1994) J. Biol. Chem. 269, 21191-21197). This protein enhances the catalytic efficiency of t-PA-dependent plasmin generation by 60-fold (Cesarman, G. M., Guevara, C. A., and Hajjar, K. A. (1994) J. Biol. Chem. 269, 21198-21203). Here, we demonstrate that annexin II is constitutively translocated to the endothelial cell surface within 16 h of biosynthesis, and that cell surface annexin II comprises 4.3 +/- 1.0% of the total cellular pool. Exogenous 125I-annexin II bound to EGTA-washed endothelial cells with high affinity (Kd 49 nM) and in a calcium-dependent (I50 = 3 microM), phospholipid-sensitive manner. Peptides KASMKGLGTDED and YDSMKGKGTRDK, mimicking the calcium-binding "endonexin" motif (KGXGT) of annexin II, blocked its interaction with endothelial cells. Recombinant annexin II, bearing the calcium-binding site substitution D161A of core repeat 2, failed to compete with binding of the wild type protein to the cell surface, while E246A and D321A mutants, corresponding to core repeats 3 and 4, behaved as effective competitors. These data suggest that translocated annexin II interacts with cell surface phospholipid via a high affinity calcium-dependent binding site that includes residues 118-122 (KGLGT) and the coordinating Asp161 of core repeat 2. Thus, calcium-regulated expression of annexin II on the endothelial cell surface may play a central role in control of plasmin-mediated processes.

Amino Acid Sequence↗
PubMed1995

Karyotypic evolution in a granulocytic sarcoma developing in a myeloproliferative disorder with a novel (3;4) translocation.

A 59-year-old man presented with a granulocytic sarcoma arising in the manubrium, and splenomegaly. The blood count showed 1.2 x 10(9)/l eosinophils and a marrow aspirate was hypercellular with eosinophilia. Cytogenetic analysis of the marrow revealed a novel t(3;4) (p13;q12) and analysis of cells aspirated from the granulocytic sarcoma showed the same abnormality and an additional trisomy 8. Intensive chemotherapy and local radiotherapy led to resolution of the chest mass but persistence of the chromosome translocation in the marrow.

Chromosomes, Human, Pair 3↗
PubMed1994

An endothelial cell receptor for plasminogen/tissue plasminogen activator. I. Identity with annexin II.

Sequencing of two internal peptides from the putative human endothelial cell tissue plasminogen activator (t-PA) receptor identified an analog of the calcium- and phospholipid-binding protein, annexin II (Ann-II). The polymerase chain reaction-derived, full-length cDNA revealed complete sequence identity with the heavy chain of Ann-II, and ligand-precipitated receptor protein immunoreacted specifically with a monoclonal antibody to Ann-II. Transfected 293 cells bound plasminogen (Kd = 114 nM; Bmax = 347,000) as well as t-PA (Kd = 48 nM; Bmax = 380,000). Antisense oligonucleotides directed against endothelial cell Ann-II mRNA inhibited binding of both t-PA and plasminogen by 49% and 38%, respectively. The K307T mutant of Ann-II expressed on 293 cells failed to bind plasminogen, while the K328I mutant bound this ligand in a manner equivalent to the wild-type. Binding of plasminogen to both the wild-type and the K328I mutant was blocked by pretreatment of 293 cells with carboxypeptidase B. These data suggest a novel mechanism whereby a plasmin-like serine protease may cleave Ann-II at Lys307-Arg308, exposing a new carboxyl-terminal lysine residue (Lys307) for binding and efficient activation of plasminogen.

Amino Acid Sequence↗
PubMed1981

Mouse liver cell culture. I. Hepatocyte isolation.

A method for isolation of mouse liver cells by a two-step perfusion with calcium and magnesium-free Hanks' salt solution followed by a medium containing collagenase is described. Several variations of the commonly used procedure for rat liver cell isolation were quantitatively compared with respect to cell yield and viability. The optimal isolation technique involved perfusion through the hepatic portal vein and routinely produced an average of 2.3 x 10(6) viable liver cells/g body weight. Optimal perfusate collagenase concentration was found to be 100 U of enzyme activity per milliliter of perfusate. Light and electron microscopic evaluation of liver morphology after several steps of the isolation showed distinct morphologic changes in hepatocytes and other liver cells during perfusion. After perfusion with Hanks' calcium- and magnesium-free solution, many hepatocytes exhibited early reversible cell injury. These changes included vesiculation and slight swelling of the endoplasmic reticulum as well as mitochondrial matrix condensation. Subsequent to perfusion with collagenase, the majority of hepatocytes appeared connected to one another only by tight junctional complexes at the bile canaliculi. Multiple evaginations were seen on the outer membrane resembling microville and probably represented the remains of cell-to-cell interdigitations between hepatocytes and sinusoidal lining cells from the space of Disse. The cytoplasmic injury seen after Hanks' perfusion was reversed after collagenase perfusion. After mechanical dispersion, isolated mouse hepatocytes were spherical in shape and existed as individual cells; many (80 to 85%) were binucleated under hase contrast light microscopy. By electron microscopy, cells appeared morphologically similar in cytoplasmic constitution to that seen in intact nonaltered liver cells.

Animals↗
PubMedDate not supplied

Intracardiac blood flow velocities and cardiac output in normal fetuses: a prospective pulsed Doppler echocardiographic study.

Two dimensional and pulsed Doppler echocardiographic studies were performed in human fetuses with the aim to establish normal values for blood flow velocities and cardiac output in Indian subjects. Thirteen pregnant mothers were prospectively followed up at 4 weeks interval from 19 to 40 weeks of gestation. Blood flow velocity spectra across aortic, pulmonary, mitral and tricuspid valves were analyzed to obtain peak flow velocity (cm/sec) and velocity time integral. Aortic and pulmonary diameters were measured at the valve level from two dimensional echocardiographic images and ventricular stroke volume calculated. The values were plotted against fetal age (weeks) and fetal weight (gms). Our results showed that there is a linear increase of the measured Doppler data, with increasing gestational age and weight. These values may be used as a reference for the Indian population.

Blood Flow Velocity↗