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W S Lynn

Publications and source records attributed to W S Lynn.

At least 19 recordsLinked to original sources
PubMed2001

The ataxia-telangiectasia gene product may modulate DNA turnover and control cell fate by regulating cellular redox in lymphocytes.

The ATM kinase, when activated postnatally, exerts multiple functions to prevent the onset of ataxia-telangiectasia (AT). Using freshly isolated thymocytes from Atm-/- mice that were under stress during postnatal differentiation, we noted that thiol redox activity, as indicated by reduction of the tetrazolium MTS, and DNA turnover activity, as indicated by incorporation of [(3)H]thymidine into DNA, were both greatly increased compared with activities in thymocytes from Atm+/+ mice. This increased thymidine incorporation could be suppressed by the thiol N-acetylcysteine. In primary noncycling splenocytes, mitogens proportionally increased both the rate of [(3)H]thymidine incorporation and the rate of reduction of MTS. The mitogen-induced activities in splenocytes were not affected by ATM but were suppressed by the calcineurin-dependent inhibitor FK-506, which has no effect on these activities in thymocytes. These findings suggest that increased [(3)H]thymidine incorporation and reducing power indicate increased cell cycling in mitogenically stimulated splenocytes, whereas these two indicators represent increased FK-506-independent DNA turnover activities in thymocytes. Thus, a primary function of ATM is to activate the redox-sensitive checkpoint required for down-regulation of DNA turnover activities in developing lymphocytes. Cell-cycling checkpoints in undamaged quiescent lymphocytes are not activated by ATM with mitogenic stimulation. ATM may suppress abnormal DNA turnover and the resultant oncogenesis by regulating cellular thiol redox pathways.

Acetylcysteine↗
PubMed1996

Long-term cultivation and productive infection of primary thymocyte cultures by a thymocytopathic murine retrovirus.

ts1, a mutant of MoMuLV, selectively kills T cells and neurons in the infected host resulting in neuroimmunodegeneration. In the infected thymus there is an early increase in mitosis of thymocytes followed by rapid death, suggesting that thymocyte death may be induced by viral mitogenic activation. Studies on thymocytes obtained from ts1-infected mice indicated that the ts1-induced depletion of thymocytes is mediated through activation-induced death by apoptosis. To further investigate the interaction between ts1 and thymocytes, we have established long-term primary murine thymocyte cultures by placing the thymocytes together with thymic remnants in culture medium containing IL-2 and IL-7. These thymocytes retained their immature phenotype and we susceptible to infection by ts1 and its parental wild-type MoMuLV. ts1-infected thymocytes proliferated initially at accelerated rate but subsequently produced more infectious virus and died much faster than control or MoMuLV-infected thymocytes. These in vitro studies to some extent reflect our in vivo studies reported previously.

Animals↗
PubMed1995

Neuroimmunodegeneration: do neurons and T cells use common pathways for cell death?

In syndromes of pediatric neuroimmunodegeneration (NID), certain neurons and T cells degenerate and disappear during early development at an accelerated rate without alerting the peripheral immune cells. Current studies of some of these NID syndromes suggest that the primary cause of neuronal and T cell death is an imbalanced cytokine signaling system with a dysfunctional redox status, and that the loss of T cells and neurons may be secondary to impaired functions of their accessory supportive cells. These dysfunctions include inappropriate production of developmental cytokines, inadequate secretion of reductants, and disregulation of excitotoxic amino acid metabolism. Two examples of pediatric NID in humans are ataxia telangiectasia and pediatric human immunodeficiency virus infection. An animal model is retrovirus-induced T and neuronal cell loss in neonatal mice infected with a neuroimmunopathogenic mutant, ts1, of the Moloney murine leukemia virus. Because both thymic and neuronal components share many growth factors and developmental signals, it is likely that disregulation of these signals would lead to concomitant dysfunction of neuronal and thymic cells. In this review, we focus on the pathogenic mechanisms involved in these developmental NID syndromes with the objective of identifying common pathogenic factors and pathways responsible for the concurrent losses of both neurons and T cells.

Animals↗
PubMed1991

Perturbation of host-cell membrane is a primary mechanism of HIV cytopathology.

Cytopathic viruses injure cells by a number of different mechanisms. The mechanism by which HIV-1 injures T cells was studied by temporally examining host-cell macromolecular syntheses, stages of the cell cycle, and membrane permeability following acute infection. T cells cytopathically infected at an m.o.i. of 1-5 grew normally for 24-72 hr, depending on the cell line, followed by the first manifestation of cell injury, slowing of cell division. At that time significant amounts of unintegrated HIV DNA and p24 core protein became detectable, and acridine orange flow cytometric cell cycle studies demonstrated the presence of fewer cells in the G2/M stage of the cell cycle. There was no change in the frequency of cells in the S-stage, and metabolic pulsing with radioactive precursors demonstrated that host-cell DNA, RNA, and protein syntheses were normal at that time and normal up to the time cells started to die (approximately 24 hr later), when all three decreased. Cellular lipid synthesis, however, was perturbed when cell multiplication slowed, with phospholipid synthesis reduced and neutral lipid synthesis enhanced. Permeability of the host-cell membrane to small molecules, such as Ca2+ and sucrose, was slightly enhanced early postinfection, and by the time of slowing of cell division, host membrane permeability was greatly increased to both Ca2+ and sucrose (Stokes radius 5.2 A) but not to inulin (Stokes radium 20 A). These changes in host-cell membrane permeability and phospholipid synthesis were not observed in acutely infected H9 cells, which are not susceptible to HIV cytopathology. Thus, HIV-1 appeared to predominantly injure T cells by perturbing host-cell membrane permeability and lipid synthesis, which is similar to the cytopathic mechanisms of paramyxoviruses.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Neutrophil elastase activity and superoxide production are diminished in neutrophils of alcoholics.

Several lines of evidence indicate that neutrophil elastase and oxidants secreted by phagocytic inflammatory cells play key roles in the development of centrilobular emphysema. A recent report suggests that ethanol consumption may have a protective role against this disease in smokers. The aim of this study was to examine the effect of ethanol consumption on neutrophil elastase activity and superoxide production of peripheral blood neutrophils. These activities were measured in neutrophils from 52 male intoxicated patients and compared to activities in neutrophils from 20 male volunteers. Neutrophils from intoxicated patients contained 31% less elastase activity than that found in controls, 0.99 +/- 0.27 versus 1.44 +/- 0.23 micrograms/10(6) neutrophils (p less than 0.0001) and produced 25 to 27% less superoxide than controls in response to phorbol 12-myristate-13-acetate, 0.90 +/- 0.17 versus 1.2 +/- 0.21 nmol/min/10(6) PMN (p less than 0.0001) or N-formylmethionylleucylphenylalanine, 0.64 +/- 0.19 versus 0.88 +/- 0.24 (p less than 0.001). In follow-up studies of 10 patients admitted for acute alcoholism, elastase activity and superoxide production remained low for 2 to 4 days. After 6 to 10 days, elastase activity and superoxide production were significantly greater than they were at Day 0 and approached normal levels. Neutrophils isolated from blood samples of healthy abstaining donors, which had been exposed to ethanol or to plasma from inebriated patients for 16 to 20 h, showed no loss of elastase activity or superoxide production.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Inhibition of human immunodeficiency virus (HIV-1) infection by diphenylhydantoin (dilantin) implicates role of cellular calcium in virus life cycle.

Details of the molecular interactions between human immunodeficiency virus (HIV-1) and its host cell during the infection process are not entirely clear. Building on recent reports by Lehr and Zimmer (1986, DMW 111, 1001-1002) that the membrane-reactive, anti-epileptic drug diphenylhydantoin (dilantin or phenytoin) (PHT) inhibited binding of HIV to lymphocytes, we hypothesized that understanding the relevant effects of this drug on cells may shed light on aspects of HIV-1 infection. We found that PHT inhibited, in a dose-dependent manner, de novo infection of various T-cell lines as well as a monocytic cell line. Moderate inhibition of HIV-1 infection was observed with drug concentrations that are therapeutic in vivo for epilepsy (approximately 20 micrograms/ml), and no concentrations used induced deleterious effects on cell growth or viability. Surprisingly, treatment of chronically infected H9 cells reduced HIV p24 expression within 1-6 weeks according to dose. This apparent induction into latency was not inhibited by cotreatment of the chronically infected cells with 5-azacytidine, which indicated that PHT was not inducing latency by induction of methylation of the viral DNA. Flow cytometric analysis demonstrated that PHT did not significantly reduce cell-surface expression of CD4. The possibility remained that the drug inhibited HIV infection due to its known effects on calcium-dependent cellular processes. Subsequent measurements of intracellular calcium demonstrated that an increase of [Ca2+]i occurred at least 24 hr postinfection, prior to synthesis of detectable viral structural protein p24, and that this virus-induced increase in [Ca2+]i was not due to binding of HIV to the cell. This HIV-induced rise in [Ca2+]i was significantly inhibited by PHT. PHT demonstrated variable inhibitory effects on infection of normal PHA-stimulated PBLs cultured in vitro, but it was synergistic to low-dose AZT (0.01 microgram/ml) in inhibiting infection of cell lines. Because of the known inhibitory effects of PHT on calcium-dependent biochemical processes in the cell, inhibition of HIV-1 infection by PHT suggests that calcium may play a role in HIV infection and maintenance. The drug may also be a candidate therapy for individuals infected with HIV.

CD4-Positive T-Lymphocytes↗
PubMed1988

Human immunodeficiency virus (HIV-1) cytotoxicity: perturbation of the cell membrane and depression of phospholipid synthesis.

The molecular mechanism(s) by which human immunodeficiency virus (HIV-1) injures a T-cell line was studied. A pathological role for viral env proteins, which are inserted into the plasma membrane, has been previously demonstrated for HIV as well as other retroviruses which are cytopathic. We therefore initiated studies examining whether perturbations of the cell membrane or membrane-associated biochemical events may be occurring in cells acutely infected with HIV and whether such perturbations, if present, may be responsible for cytopathology. A human T-cell line (ERIC), which is sensitive to the cytopathic effects of HIVs, was infected with HTLV-IIIB and its membrane permeability to cations and its lipid metabolism were studied coincident with the peak expression of viral p24 and with the first sign of cytopathology (slowing of cell division) 72 to 96 hr after infection. It was found that the rate of influx of Ca2+ into the cell increased over that of uninfected cells and that phospholipid synthesis, primarily phosphatidylcholine, became depressed. Diacylglycerol, which serves both as an intermediate for synthesis of phospholipids and as a second-messenger for lymphocyte activation, was also greatly reduced. However, triglyceride synthesis was enhanced, indicating that not all lipid metabolic pathways were being shut down. This decreased membrane-synthetic ability and reduced second-messenger for cell division are likely to be important causes of HIV-1 cytopathology in ERIC cells. This hypothesis was supported by our finding that HIV cytopathology of ERIC cells could be partially prevented by treatment with compounds (diacylglyceride or PMA and transiently by oleic acid) which either replenish diacylglycerol in the infected cell and/or activate protein kinase C or phosphocholine cytidyltransferase, the latter being the rate-limiting step in synthesis of the major structural phospholipid in most cells.

Calcium↗
PubMed1987

Biochemical properties of tracheobronchial mucins from cystic fibrosis and non-cystic fibrosis individuals.

Tracheobronchial mucins from healthy individuals and from patients with bronchial asthma or cystic fibrosis (CF) were isolated from lung mucus, purified, and their chemical and physical properties compared. Normal and asthmatic mucins required both a dissociating and a reducing agent for solubilization and exhibited identical chromatographic behavior on Sepharose 4B, Sepharose 2B, and hydroxylapatite and similar amino acid and carbohydrate compositions. In contrast, 1) CF lung mucins were solubilized in the absence of dissociating and/or reducing agents and 2) the majority of the CF mucins analyzed was eluted in the included volume of Sepharose 4B with Kd values of 0.3 +/- 0.1 rather than in the void volume and thus appeared smaller than normal and asthmatic mucins. The lower molecular weight mucins in CF sputum apparently are produced by bacterial or inflammatory cell proteinases since radiolabelled asthmatic mucin was digested to smaller fragments when incubated with crude CF lung mucosal samples. Furthermore, mucins secreted by tracheal explants from CF and from non-CF individuals eluted in the void volume on Sepharose 4B, suggesting that CF tracheobronchial mucins were not inherently smaller than non-CF mucins.

Adolescent↗
PubMed1984

Structure elucidation by one- and two-dimensional 360- and 500-MHz 1H NMR of the oligosaccharide units of two glycoproteins isolated from alveoli of patients with alveolar proteinosis.

The structure of the oligosaccharide units of the glycoproteins of Mr 36,000 and 62,000 isolated from alveoli of patients with alveolar proteinosis have been determined by one- and two-dimensional 1H NMR spectroscopy at 500 and 360 MHz. Bi-, tri-, and tetraantennary glycans of N-acetyllactosaminic type have been found in high percentage. They are 1----6 monofucosylated and fully sialylated, the ratio NeuAc(2----3)/NeuAc X (2----6) increasing with increasing degree of branching.

Chemical Phenomena↗
PubMed1984

Control of cellular influx in lung and its role in pulmonary toxicology.

The pulmonary influx of cytotoxic inflammatory cells, normally, in response to external toxins, is now thought to be etiologic in many of the disease syndromes of man, such as bronchitis and emphysema. Many types of effector inflammatory cells are involved, e.g., eosinophils, neutrophils, T-lymphocytes, monocytes. The diseases are characterized either by tissue destruction or by tissue hyperplasia. Agents which initiate the influx and cytotoxic secretions by these cells are legion and in general are not cell-specific. They include agents, such as phorbol esters, formyl peptides-complement fragments, elastin fragments, fatty acids (leukotrienes) as well as many uncharacterized excretions of inflammatory cells themselves, which react with specific receptors on the inflammatory cells, and secreted proteins such as fibronectin. Other agents, such as linoleic acid, digitonin and hydroxy fatty acids which are not bound by specific receptors also activate motility of inflammatory cells. The precise role of the above multiple cytotoxins in specific cellular fluxes in most pulmonary disease remains undefined. Similarly, the mechanism of cytotoxicity used by specific invading cells in specific pulmonary syndromes remains unclear. In general, macrophages are thought to destroy using specific proteases, neutrophils use oxidant radicals and proteases and eosinophils use basic surface active peptides. T-cells kill by unknown mechanisms. However, in specific clinical syndromes, it is usually not clear which cell is the cytotoxic culprit, nor is the mechanism of destruction usually known.

Animals↗
PubMed1984

Alveolyn--structure and source: a review.

Alveolyn is a unique secretory glycoprotein of 250,000 molecular weight (MW) that is found in distal pulmonary secretions. Several glycoproteins of 130,000 MW, 80,000 MW, 62,000 MW, and 36,000 MW have also been found to be present in the alveolar secretions, and it was found that these glycoproteins were proteolytic fragments of the much larger molecular glycoprotein. It is also a major protein in human amniotic fluid, presumably a product of alveolar secretions. It is also secreted by a clone of pulmonary fetal type II cells. Preliminary results indicate that two of the proteolytic fragments of 62,000 MW and 36,000 MW contain alternate collagenous and noncollagenous domains in the same polypeptide chain. The presence of collagenous domains in these glycoproteins was also confirmed by their susceptibility to digestion with collagenase and the presence of Gly-Pro-Hyp-Gly-type sequence in the peptide chain. Very little is known about the tertiary structure of the protein, except that its fragments bind phospholipids and probably facilitate transfer of the lipid to air-water interfaces.

Amino Acid Sequence↗
PubMed1983

Characterization of a glycoprotein isolated from a continuous tumor-cell line of human lung carcinoma.

A glycoprotein with a molecular weight of 62 000 has been isolated from a tumor-cell line, A549, and purified to homogeneity by gel chromatography. The glycoprotein contained sialic acid, galactose, mannose, N-acetylglucosamine and a relatively high amount of glutamic acid and proline. The data indicated that the overall composition of this glycoprotein was different from that of the glycoprotein of Mr 62 000 isolated from lung lavage of patients with alveolar proteinosis. The glycoprotein did not react with the antiserum raised against glycoprotein of Mr 62 000 isolated from lung lavage of patients with alveolar proteinosis.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1983

Effects of bleomycin and methylprednisolone on the biosynthesis of oligosaccharide-lipids and glycoproteins in lung.

Tissues from rabbit lung were found to incorporate radioactivity from [3H]mannose into the oligosaccharide of a polar lipid soluble in chloroform/methanol/water (10:10:3, by vol.). Only one oligosaccharide-lipid was formed and the composition of the radiolabelled carbohydrate moiety was Glc3Man9(GlcNAc)2. An antitumour antibiotic, bleomycin, and an anti-inflammatory steroid, methylprednisolone, partially inhibited the incorporation of [3H]mannose into oligosaccharide-lipids and in addition resulted in the production of two new components, Man5(GlcNAc)2 and Man2(GlcNAc)2. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the glycoproteins synthesized from the oligosaccharide-lipid intermediates showed labelled components with Mr greater than 200000, 130000, 80000 and 62000. The addition of the drugs resulted in the same pattern with the addition of a new component of Mr 36000. Endoglucosaminidase H-treatment of the glycopeptides isolated from the Pronase-digested glycoproteins indicated that the oligosaccharide units in the glycoproteins were of the high-mannose-type.

Animals↗
PubMed1983

Characterization of pepsin-resistant peptides present in a glycoprotein isolated from lung lavage of normal rabbit.

A glycoprotein of Mr 36 000 has been isolated from lung lavage of normal rabbit and purified to homogeneity by gel chromatography. Three peptides containing hydroxyproline and nearly 30% glycine have been isolated and purified from pepsin-digested native glycoprotein. Partial NH2-terminal amino acid sequence analysis on one of the peptides indicated the presence of -Gly-Pro-Hyp-Gly- sequence in the peptide chain, suggesting that collagen-like region(s) may be present in this glycoprotein.

Amino Acid Sequence↗