Recombinant tumour necrosis factor-alpha and platelet-activating factor synergistically increase intercellular adhesion molecule-1 and E-selectin-dependent neutrophil adherence to endothelium in vitro

Neutrophil adhesion to microvascular endothelium at sites of acute inflammation is regulated by both chemotactic peptides and lipid-derived mediators. Tumour necrosis factor-alpha (TNF-alpha) is a pro-inflammatory peptide that up-regulates endothelial expression of intercellular adhesion molecule-1 (ICAM-1) and endothelial leucocyte adhesion molecule-1 (E-selectin), while platelet-activating factor (PAF) is a potent lipid mediator that induces vascular changes via an unknown mechanism. Both have been shown to increase leucocyte-endothelial adhesion in various in vitro models of acute inflammation; however, the combined effects of recombinant TNF-alpha (rTNF-alpha) and PAF on neutrophil-endothelium adhesion have not been well described. In this study, we found rTNF-alpha at 0.5 ng/ml and PAF at 10 microM acted synergistically to increase neutrophil adherence to cultured umbilical vein endothelial cells 4 hr after stimulation. This increased neutrophil-endothelial adhesion was, in part, dependent on up-regulated expression of ICAM-1 and E-selectin since application of anti-ICAM1 and anti-E-selectin F(ab')2 fragments markedly diminished adhesion. Cultures stimulated with rTNF-alpha (0.5 ng/ml) or PAF (10 microM) alone did not show a significant increase in neutrophil adhesion, and neither ICAM-1 nor E-selectin expression was up-regulated as determined by flow cytometric analysis of endothelial cells. These results indicate that rTNF-alpha and PAF act synergistically to increase neutrophil-endothelial adhesion by stimulating endothelial expression of ICAM-1 and E-selectin and, thus, may play important roles in the onset and severity of acute inflammatory reactions.     

Molecular dynamics simulations of small DNA plasmids: effects of sequence and supercoiling on intramolecular motions

Small (600 base pair) DNA plasmids were modeled with a simplified representation (3DNA) and the intramolecular motions were studied using molecular mechanics and molecular dynamics techniques. The model is detailed enough to incorporate sequence effects. At the same time, it is simple enough to allow long molecular dynamics simulations. The simulations revealed that large-scale slithering occurs in a homogeneous sequence. In a heterogeneous sequence, containing numerous small intrinsic curves, the centers of the curves are preferentially positioned at the tips of loops. With more curves than loop tips (two in unbranched supercoiled DNA), the heterogeneous sequence plasmid slithers short distances to reposition other curves into the loop tips. However, the DNA is immobilized most of the time, with the loop tips positioned over a few favored curve centers. Branching or looping also appears in the heterogeneous sequence as a new method of repositioning the loop tips. Instead of a smooth progression of increasing writhing with increasing linking difference, theoretical studies have predicted that there is a threshold between unwrithed and writhed DNA at a linking difference between one and two. This has previously been observed in simulations of static structures and is demonstrated here for dynamic homogeneous closed DNA. Such an abrupt transition is not found in the heterogeneous sequence in both the static and dynamic cases.     

A comparative study of synchronised and conventional culture methods on the micronucleus dose-response curve

The involvement of GABAA and GABAB receptors in neural mechanisms responsible for the production of theta rhythms in hippocampal formation (HPC) slices is addressed in the present study. In a number of papers published in the last decade, we have demonstrated that theta-like activity can be successfully recorded in the limbic cortex maintained in vitro when the cholinergic agonists, acetylcholine, carbachol or muscarine, were added to the bath. Recently, we have also shown a strong GABAA modulation of the cholinergic-induced in vitro theta-like activity. This study presents a report of the first demonstration of in vitro theta-like field responses induced a consequence of simultaneously inhibiting hippocampal GABAA and GABAB receptors. HPC slices (350 microns) were maintained in a gas-liquid interface chamber (35 degrees C). Theta-like activity was induced in the presence of bath perfusion of bicuculline (GABAA antagonist) and 2-hydroxysaclophen (GABAB antagonist). This in vitro induced field response was antagonized both by muscimol (GABAA agonist) and baclophen (GABAB agonist). In addition, the experiments presented here revealed that bicuculline/2-hydroxysaclophen-induced in vitro theta-like activity also had a strong cholinergic M1 involvement: it was abolished by hemicholinium-3 (choline transport blocker) and pirenzepine (specific antagonist of M1 receptor), but not by gallamine (specific antagonist of M2 receptor). The results of the present study provided further evidence for a strong GABAergic/cholinergic interaction in the neural mechanism responsible for production of theta-like activity in the hippocampal formation slices.     

Causal memory: definitions,implementation, and programming

Summary The abstraction of a shared memory is of growing importance in distributed computing systems. Traditional memory consistency ensures that all processes agree on a common order of all operations on memory. Unfortunately, providing these guarantees entails access latencies that prevent scaling to large systems. This paper weakens such guarantees by definingcausal memory, an abstraction that ensures that processes in a system agree on the relative ordering of operations that arecausally related. Because causal memory isweakly consistent, it admits more executions, and hence more concurrency, than either atomic or sequentially consistent memories. This paper provides a formal definition of causal memory and gives an implementation for message-passing systems. In addition, it describes a practical class of programs that, if developed for a strongly consistent memory, run correctly with causal memory. Mustaque Ahamad is an Associate Professor in the College of Computing at the Georgia Institute of Technology. He received his M.S. and Ph.D. degrees in Computer Science from the State University of New York at Stony Brook in 1983 and 1985 respectively. His research interests include distributed operating systems, consistency of shared information in large scale distributed systems, and replicated data systems. James E. Burns received the B.S. degree in mathematics from the California Institute of Technology, the M.B.I.S. degree from Georgia State University, and the M.S. and Ph.D. degrees in information and computer science from the Georgia Institute of Technology. He served on the faculty of Computer Science at Indiana University and the College of Computing at the Georgia Institute of Technology before joining Bellcore in 1993. He is currently a Member of Technical Staff in the Network Control Research Department, where he is studying the telephone control network with special interest in behavior when faults occur. He also has research interests in theoretical issues of distributed and parallel computing especially relating to problems of synchronization and fault tolerance.This work was supported in part by the National Science Foundation under grants CCR-8619886, CCR-8909663, CCR-9106627, and CCR-9301454. Parts of this paper appeared in S. Toueg, P.G. Spirakis, and L. Kirousis, editors,Proceedings of the Fifth International Workshop on Distributed Algorithms, volume 579 ofLecture Notes on Computer Science, pages 9–30, Springer-Verlag, October 1991The photograph of Professor J.E. Burns was published in Volume 8, No. 2, 1994 on page 59This author's contributions were made while he was a graduate student at the Georgia Institute of Technology. No photograph and biographical information is available for P.W. Hutto Gil Neiger was born on February 19, 1957 in New York, New York. In June 1979, he received an A.B. in Mathematics and Psycholinguistics from Brown University in Providence, Rhode Island. In February 1985, he spent two weeks picking cotton in Nicaragua in a brigade of international volunteers. In January 1986, he received an M.S. in Computer Science from Cornell University in Ithaca, New York and, in August 1988, he received a Ph.D. in Computer Science, also from Cornell University. On August 20, 1988, Dr. Neiger married Hilary Lombard in Lansing, New York. He is currently a Staff Software Engineer at Intel's Software Technology Lab in Hillsboro, Oregon. Dr. Neiger is a member of the editorial boards of theChicago Journal of Theoretical Computer Science and theJournal of Parallel and Distributed Computing.     

Successful in vivo and ex vivo transfection of pulmonary artery segments in lung isografts

OBJECTIVE: Gene transfer to lung grafts may be useful in ameliorating ischemia-reperfusion injury and rejection. Efficient gene transfection to the whole organ may prove problematic. Proximal pulmonary artery endothelial transfection might provide beneficial downstream effects on the whole graft. The aim of this study was to determine the feasibility of transfecting proximal pulmonary artery segments in lung isografts. METHODS: Male Fischer rats were divided into six groups. In vivo transfection: In group I (n = 7), a proximal segment of the left pulmonary artery was isolated and injected with saline solution by means of a catheter inserted through the right ventricle. After an exposure period of 20 minutes, clamps were removed and blood flow was restored. In group II (n = 7), the isolated arterial segments were injected with adenovirus carrying the Escherichia coli LacZ gene encoding for beta-galactosidase. Ex vivo transfection: In group III (n = 5), arterial segments were injected ex vivo with saline solution and in group IV (n = 5) with the adenovirus construct. In group V (n = 6), arteries were injected with saline solution and in group VI (n = 11) with liposome chloramphenicol acetyl transferase cDNA. In groups I to IV, animals were killed on postoperative day 3 and transgene expression was assessed by Bluo-Gal staining. In groups V and VI, animals were killed on postoperative day 2 and transgene expression was assessed by chloramphenicol acetyl transferase activity assay. RESULTS: Transgene expression was detected grossly and microscopically in endothelial and smooth muscle cells of pulmonary artery segments from all surviving animals of groups II and IV. In group VI, chloramphenicol acetyl transferase activity was significant in all assessed arterial segments. CONCLUSION: Significant transgene expression is observed in proximal pulmonary artery segments after both in vivo and ex vivo exposure.     

Regulation by gangliosides and sulfatides of phospholipase A2 activity against dipalmitoyl- and dilauroylphosphatidylcholine in small unilamellar bilayer vesicles and mixed monolayers

The modulation by gangliosides GM1 and GD1a, and sulfatide (Sulf) of the activity of porcine pancreatic phospholipase A2 was studied with small unilamellar vesicles of dipalmitoylphosphatidylcholine (L-dpPC) and lipid monolayers of dilauroylphosphatidylcholine (L-dlPC). The presence of Sulf always led to an increase of the maximum rate of the enzymatic reaction, irrespective on whether the vesicles were above, in the range of, or below the bilayer transition temperature. Sulf did not modify the latency period for the reaction that is observed at the bilayer transition temperature. Gangliosides inhibited the maximum rate of enzymatic activity bilayer vesicles in the gel phase but the effect was complex. When the reaction was carried out at a temperature within the range of the bilayer phase transition, the gangliosides inhibited the maximal rate of the reaction in proportion to their content in the bilayer. However, at the same time the latency period observed with vesicles of pure phospholipid at this temperature was shortened in proportion to the mole fraction of gangliosides in the bilayer. At temperatures above the bilayer phase transition, gangliosides stimulated the activity of PLA2. Preincubation of the enzyme with Sulf or gangliosides did not affect the activity against bilayer vesicles of pure substrate. These glycosphingolipids did not modify the rate or extent of desorption of the enzyme from the interface, nor the pre-catalytic steps for the interfacial activation of PLA2, or the enzyme affinity for the phospholipid substrate. Also, the activity of the enzyme was not altered irreversibly by glycosphingolipids. Our results indicate that Sulf and gangliosides modulate the catalytic activity of PLA2 at the interface itself, beyond the initial steps of enzyme adsorption and activation, probably through modifications of the intermolecular organization and surface electrostatics of the phospholipid substrate.     

Sulfated glucuronyl glycolipids and gangliosides in the optic nerve of humans

Pathologically delayed visual evoked potentials may be present in patients with neuropathy associated with IgM M-proteinemia, which is directed against myelin-associated glycoprotein and sulfated glucuronyl glycolipids (SGGLs), but there are no reports of these antigens in the optic nerve. We recently examined human optic nerve and occipital lobe tissues for the occurrence of SGGLs using the technique of immunostaining on thin-layer chromatographic plates and found them in the optic nerve, but not the occipital lobe. SGGLs in the optic nerve may represent target antigens for CNS involvement by the M-protein in patients with neuropathy. We also studied the ganglioside composition of the optic nerve and found it different from that of the brain. Human optic nerve is characterized by an abundance of the b-series gangliosides, including GD1b, GT1b, and GQ1b. GD1a, which is usually a major component of brain gangliosides, is only a minor species of the optic nerve ganglioside fraction.     

Multiple pituitary hormone deficiencies in a patient with spinocerebellar ataxia: magnetic resonance imaging and hormonal studies

Degenerative spinocerebellar ataxia has a rare association with hypogonadotropic hypogonadism. In this report we present the results of the detailed endocrine evaluation and magnetic resonance imaging in one such patient. A 20-year-old male with progressive cerebellar ataxia, hypogonadism, and short stature was investigated. Basal testing revealed hypogonadotropic hypogonadism (LH < 5 mU/L, FSH < 5 mU/L, testosterone 2.5 nM/L). There was no rise in LH after stimulation with LHRH, peak LH level being < 5 mU/L. Insulin hypoglycemia testing was consistent with GH deficiency, with peak GH being 3.2 mU/L. On TRH stimulation, there was no significant rise in prolactin, though the TSH response was normal. Magnetic resonance imaging revealed cerebellar atrophy. The anterior pituitary was atrophic, with a height of 1.4 mm. The posterior pituitary and the pituitary stalk were normal in size and position. This patient with degenerative spinocerebellar ataxia had multiple pituitary hormone deficiencies. The results of our endocrine evaluation and MR imaging lead us to believe that these deficits may result from a lesion at the level of the pituitary gland.