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Papers by Janet Ludwig

The Journal of Immunology

The phlogistic actions of six molecular species of platelet-activating factor (PAF) (1-O-alkyl-PA... more The phlogistic actions of six molecular species of platelet-activating factor (PAF) (1-O-alkyl-PAF homologs, 16:0-, 18:0- and 18:1-alkyl-PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC) and their respective 1-acyl-PAF analog counterparts, 16:0-, 18:0- and 18:1-acyl-PAF, 1-acyl-2-acetyl-sn-glycero-3-phosphocholine (AGPC)) were assessed relative to five human neutrophilic polymorphonuclear leukocyte (PMN) functional responses: 1) lysosomal enzyme secretion; 2) specific desensitization to 16:0-AGEPC-induced lysosomal enzyme secretion; 3) O2- production; 4) chemotaxis; and 5) priming for enhanced O2- production. With respect to inducing lysozyme secretion, 18:0-AGEPC was 30- and 75-fold less potent than 16:0-AGEPC and 18:1-AGEPC, respectively, and was 25- and 40-fold less potent for inducing beta-glucuronidase secretion. 18:0-AGEPC was also 10-fold less active than 18:1- and 16:0-AGEPC for inducing O2- production. Thus, the rank order of potency of the alkyl-PAF homologs for ...

Inflammatory Diseases and Copper, 1982

Several trace metal ions have been shown to modify cell injury as indicated by reduction of obser... more Several trace metal ions have been shown to modify cell injury as indicated by reduction of observable pathological tissue changes after metal ion supplementation: Liver injury (Chvapil et al, 1973; Hafeman and Hoekstra, 1977; Saldeen, 1969; Suarez and Bhonsle, 1976; Cagen and Klaassen, 1979, 1980; Pani et al, 1975) induced facial eczema (Towers, 1977), rheumatoid arthritis (Simkin, 1977; Weissman, 1968), endotoxic shock (Snyder and Walker, 1976), and myocardial infarction (Chvapil et al, 1977). In most of these situations this effect has been postulated to be the result of a stabilizing effect of metal ions on lysosomes. However, the rupture of lysosomes depends not only on the intactness of the lysosomal membrane, but also on the reactivity of the cell to certain stimuli which could ultimately cause the release of lysosomal enzymes. The lysosomal stabilization may reflect the reduction of tissue injury due to other cellular mechanisms modulated by metal ions. In addition, metals of similar electronic configuration may substitute for one another in physiological properties, i.e. metalloenzymes.

Platelet-activating factor (PAF) was synthesized and released by human polymorphonuclear leukocyt... more Platelet-activating factor (PAF) was synthesized and released by human polymorphonuclear leukocytes (PMN; 5 x 10/sup 6/ ml) stimulated in the presence of /sup 3/H-acetate with the calcium ionophore A23187 (2.5 ..mu..M). The temporal incorporation of /sup 3/H-acetate into phospholipids by stimulated PMN occurred concomitantly with PAF production. Phospholipid separation of cell-associated PAF by normal phase HPLC revealed the presence of 2 peaks of /sup 3/H-activity both possessing platelet stimulating activity. The major peak of /sup 3/H-PAF coeluted with 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC) while the smaller peak coeluted with 1-O-alkyl-2-acetyl-sn-glycero-3-phosphoethanolamine/dimethylethanolamine/monomethylethanolamine. Reverse phase HPLC fractionation of the PAF activity in the choline containing region indicated the presence of 15 peaks of /sup 3/H-activity, all of which exhibited PAF activity. In addition, reverse phase HPLC of the PAF in the ethanolamine-con...

R at l i v e r m icrosom es were in c u b a te d in th e p re s e n c e o f z in c io n s and th ... more R at l i v e r m icrosom es were in c u b a te d in th e p re s e n c e o f z in c io n s and th e r a t e o f NADPH o x id a t io n and r e l a t e d m e tab o lism o f a n i l i n e and e th y lm o rp h in e by a p p r o p r ia te o x id a se s w ere s tu d ie d . A c o m p e tit iv e m echanism o f th e i n h i b i t i o n o f NADPH o x id a t io n by z in c io n was fo u n d , w ith Vmax = 1 0 .3 nm oles NADPH/min/mg p r o t e i n and = 7 .22 uM z in c . A lthough s p e c t r a l a n a ly s i s o f NADPH in th e ran g e o f 220-400 nm d id n o t 2+ show any e f f e c t o f z in c , g e l f i l t r a t i o n in d ic a te d b in d in g o f Zn to NADPH in th e m o la r r a t i o 2 :1 . The o v e r a l l fo rm a tio n c o n s ta n t o f Zn^-NADPH com plex i s 1 0 ^ '7 5 . Z inc io n a ls o i n h i b i t e d th e a c t i v i t y o f two o th e r m icrosom al drug o x id a s e s , a n i l i n e h y d ro x y la se and e th y lm o rp h in e -N -d e m e th y la se ; 50% 2+ i n h i b ...

Journal of Lipid Research, 1989

The Journal of Nutrition, 1980

The effect of zinc ions on the stability of rat liver lysosomes was studied. Zinc was added by se... more The effect of zinc ions on the stability of rat liver lysosomes was studied. Zinc was added by several methods: feeding the animals a high-zinc diet; infusion of zinc into the liver through the portal vein, or by adding zinc to the lysosomal fraction either before or after isolation of this fraction from rat liver homogenates. By all techniques, addition of zinc reduced the release of beta-glucuronidase from liver lysosomes. Lysosomes and lysosomal membranes from rats fed a high-zinc diet were found to be relatively high in zinc. These lysosomes were less fragile than lysosomes from the liver of control animals. The stabilizing effect of zinc ions could be reversed by treatment of lysosomes with phosphate buffer. We concluded that increasing the zinc content in the liver by any of these methods results in stabilization of liver lysosomes.

Several trace metals have been shown to modify cell injury as indicated by reduction of observabl... more Several trace metals have been shown to modify cell injury as indicated by reduction of observable pathological tissue changes after metal ion supplementation. An example of this is zinc ion induced protection against some of the liver injury caused by a single injection of carbon tetrachloride (CCl₄) to male Sprague-Dawley rats. Carbon tetrachloride liver injury is associated with membrane labilization as indicated by lysosomal and endoplasmic reticulum anomalies. Depressed hepatic levels of NADPH are observed during CCl₄ poisoning. Lipid metabolism is also impaired due to CCl₄ administration to animals. These biochemical manifestations of CCl₄ hepatotoxicity were studied in the presence of zinc ions in order to understand the mechanisms of the zinc protective effect against CCl₄ injury. The effect of zinc ions on the stability of rat liver lysomes was studied. Zinc was added by several methods: (1) feeding the animals a high zinc diet, (2) infusion of zinc into the liver in situ through the portal vein, or (3) by adding zinc to the lysosomal fraction either before or after isolation of this fraction from rat liver homogenates. By all techniques, addition of zinc reduced the release of β-glucuronidase from liver lysosomes, indicating increased stability of the suborganelles. The zinc induced protection against CCl₄ liver damage was evident in observations made using both light microscopy and electron microscopy. The increased release of lysosomal β-glucuronidase observed in the CCl₄ treated rats was significantly reduced by zinc administration. Also, decreases in microsomal protein synthesis and seromucoid levels due to the CCl₄ treatment were significantly ameliorated by zinc. Thus, disruption of lysosomal and endoplasmic reticulum membranes, one of the earliest signs of CCl₄ hepatotoxicity, appeared to be inhibited by pretreating the animals with zinc chloride. Depressed hepatic levels of NADPH are observed in rats administered CCl₄. Zinc chloride pretreatment of these rats significantly increased the NADPH levels in the liver. Since zinc ions bind NADPH, then the protective effect of zinc against CCl₄ toxicity may be due to stabilization of the pyridine nucleotide by zinc and the subsequent prevention of CCl₄ induced alterations of biochemical reactions dependent upon NADPH. Zinc chloride pretreatment of CCl₄ treated rats significantly reduced the CCl₄ induced hepatic triacylglycerol accumulation. Concomitant with this event is the appearance of elevated levels of newly synthesized triacylglycerols in the serum of the CCl₄ treated rats given zinc above that of the CCl₄ treated rats. Hepatic triacylglycerol synthesis is unchanged by CCl₄ or zinc treatment. Hepatic phospholipid levels which are depressed by the CCl₄ hepatotoxin are not affected by zinc treatment. However, the synthesis of phospholipids in the livers of rats treated with CCl₄ plus zinc is significantly increased. The lipid changes induced by CCl₄ and zinc dosing of rats are indicative of alterations in liver membranes thus affecting hepatic liver transport mechanisms. On the basis of the data presented, the effects of zinc ions on CCl₄ hepatotoxicity are discussed and applied to understanding the regulating role of metal ions in tissue injury. The protective effects of zinc ions against CCl₄ hepatotoxicity suggest a relationship between the zinc nutritional status of animals exposed to environmental contaminants, and the expression of the ensuing tissue damage

Platelet-activating factor (PAF) is a potent phospholipid produced by stimulated human polymorpho... more Platelet-activating factor (PAF) is a potent phospholipid produced by stimulated human polymorphonuclear leukocytes (PMN). Tritiated-PAF produced by human PMN (5 x 10â¶ cells/ml) stimulated in the presence of Â³H-acetate was separated by normal phase HPLC. PMN stimulated with the calcium ionophore A23187 (2.5 ..mu..M, final concentration) produced two peaks of Â³H-activity both of which activated platelets; the major peak (92.3% of total cpm) had the same relative retention time (RRT) as 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (C16:0-AGEPC, RRT = 1.00) when related to the retention time of the internal standard Â³HC16:O-AGEPC while the smaller peak (2.4%) had a RRT of 0.61. In contrast, PMN stimulated with the chemotactic peptide N'formyl-methionyl-leucyl-phenyl-alanine (FMLP; 10â»â¶M), opsonized zymosan (1.8 mg/ml), or phorbol myristate acetate (PMA; 20 ng/ml) produced Â³H-PAG that was separated into 5 peaks of Â³H-activity (RRT = 0.23, 0.36, 0.65, 1.00 and 1.23)....

Agents and actions. Supplements, 1981

Experimental Biology and Medicine, 1979

Summary Proteins and phospholipids but not zinc were released into the medium containing hemoglob... more Summary Proteins and phospholipids but not zinc were released into the medium containing hemoglobin-free ghosts from dog erythrocytes incubated in peroxidation-inducing agents (ascorbic acid, Fe2+, O2). The content of zinc in the pure ghost depends on the purification procedure; using phosphate buffer it amounted to 62 ± 22 μg/g protein, and using barbital buffer-extracted ghost it was three times higher. Although most of the zinc was linked to the lipid phase of the membrane, there is a certain protein moiety of membrane proteins binding more zinc than the other protein fractions. Among various fractions of lipids, zinc is linked mainly to phospholipids and this linkage is not broken by phosphate buffer. It is concluded that zinc is part of the erythrocyte ghost, linked to protein as well as lipid phase. This work is supported in part by NIH Research Grants AM 16489, ES 00790, and ES 01570. The professional assistance of Mrs. Waltraud W. Nichols is highly appreciated.

Experimental and Molecular Pathology, 1979

... 30, 349-359 (1979) Dynamics of the Healing of Skin Wounds in the Horse as Compared with the R... more ... 30, 349-359 (1979) Dynamics of the Healing of Skin Wounds in the Horse as Compared with the Rat MILOS CHVAPIL, TAD PFISTER, SIMON ESCALADA, JANET LUDWIG ... SKIN WOUNDS IN HORSES AND RATS 359 ORONSKY, AL, PERPER, RJ, and SCHRODER, HC (1973 ...

Chemico-Biological Interactions, 1980

Biochemical Pharmacology, 1975

Biochemical Pharmacology, 1976

ABSTRACT Rat liver microsomes were incubated in the presence of zinc and the rate of NADPH oxidat... more ABSTRACT Rat liver microsomes were incubated in the presence of zinc and the rate of NADPH oxidation and related metabolism of aniline and ethylmorphine by appropriate oxidases were studied. A competitive mechanism of the inhibition of NADPH oxidation by zinc was found, with Vmax = 10.3 nmoles NADP/min/mg of protein and Ki amounting to 7.22 μM zinc. In microsomes dialyzed against EDTA, addition of Mn2+ but not of Mg2+ enhanced the rate of NADPH oxidation. A complex relation of Zn2+ and Mn2+ in liver microsomes was found, the data not obeying the rigorous treatment for enzyme kinetics. The activity of aniline hydroxylase and ethylmorphine-N-demethylase was inhibited by zinc; 50 per cent inhibition was reached at 60 and 55 μM Zn2+ respectively. Another microsomal enzyme, glucose 6-phosphatase, independent of NADPH, was not affected by zinc. The content and spectral characteristics of cytochrome P-450 were not affected by zinc. It is concluded that Zn2+ inhibits oxidation of NADPH and prevents this pyridine nucleotide from functioning in the microsomal electron transport system. The possibility that Zn2+ may interfere with other ions or enzymes involved in microsomal electron transport cannot be excluded.

Archives of Biochemistry and Biophysics, 1985

Biochemical and Biophysical Research Communications, 1985

Fast atom bombardment mass spectrometry was used to identify molecular species of platelet-activa... more Fast atom bombardment mass spectrometry was used to identify molecular species of platelet-activating factor (PAF) produced by stimulated human neutrophilic polymorphonuclear leukocytes. Normal and reverse-phase high performance liquid chromatography were employed to separate the individual regions with PAF activity prior to mass spectrometric analysis. The following alkyl chain homologs of acetyl glyceryl ether phosphorylcholine (AGEPC) were found: C16:0, C17:0, C18:0 and C18:1. There was also evidence for the presence of the C15:0 homolog, as well as other species which have not yet been identified.

Biochemical and Biophysical Research Communications, 1984