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M Wozniak

Publications and source records attributed to M Wozniak.

At least 19 recordsLinked to original sources
PubMed1997

Suppression of the formation of megamitochondria by scavengers for free radicals.

In the present study we have attempted to suppress the formation of megamitochondria by scavengers for free radicals since conditions for the formation of megamitochondria are often intimately related to the generation of free radicals. We employed three different experimental conditions to induce megamitochondria in the liver: ethanol, hydrazine and chloramphenicol (CP). Scavengers for free radicals tested were: alpha-tocopherol, coenzyme Q10(CoQ10) and 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl(4-OH-TEMPO). Allopurinol (AP), a xanthine oxidase inhibitor, was also tested. Results obtained were as follows. (1) Changes observed in the liver of animals treated with ethanol, hydrazine or CP were: formation of megamitochondria; decreases in the body weight and the weight of the liver; remarkable increases in the level of lipid peroxidation; increases in the activity of xanthine oxidase. (2) 4-OH-TEMPO was most effective in improving these changes. A mechanism of the formation of megamitochondria is proposed stressing the role of free radicals in the mechanism.

Allopurinol↗
PubMed1997

Influence of structure on the antioxidant activity of indolinic nitroxide radicals.

An in vitro study was carried out to verify whether the chain length of a substituent on an indolinic nitroxide could influence its antioxidant activity in different biological environments subjected to oxidative stress. Three distinct indolinic nitroxides were synthesized and compared with vitamin E and Trolox (a hydrophilic analogue of vitamin E), where the only difference between the nitroxides was the length of the hydrocarbon chain in the 2-position of indole, namely 2 (C2), 10 (C10), and 18 (C18) carbons. All the nitroxides were effective in preventing oxidation of bovine serum albumin, but to different extents, with the longer chain derivatives being more efficient. However, the C2 compound was the most efficient in preventing lipid peroxidation in microsomal membranes. The C2 and C18 compounds, Trolox, and vitamin E protected microsomal protein oxidation to the same extent at the highest concentration used (13 microM). The nitroxide with a C10 chain was less effective in this system. The influence of these compounds on the enzymatic activity of two mitochondrial proteins subjected to oxidative stress was also studied by means of oxygraph measurements. Mitochondrial rotenone-sensitive NADH oxidase and succinate oxidase responded differently to BuOOH-induced radical chemistry, and the compounds under study also protected the activity of the two enzymes but to different extents. The results clearly demonstrate that indolinic nitroxides are very efficient antioxidants, protecting both lipids and proteins from peroxidation. The indole structure influences the antioxidant efficacy in biological systems.

Animals↗
PubMed1997

Role of free radicals in the mechanism of the hydrazine-induced formation of megamitochondria.

The effect of 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl(4-OH-TEMPO), a scavenger for free radicals, and 4-hydroxypyrazolo [3,4-d(pyrimidine)allopurinol], a xanthine oxidase inhibitor, on the hydrazine-induced changes of mitochondrial ultrastructure and those in the antioxidant system of the liver were investigated using rats as experimental animals. Animals were placed on a powdered diet containing 0.5% hydrazine for 7 d in the presence and absence of a combined treatment with 4-OH-TEMPO or allopurinol. Results obtained were as follows. 4-OH-TEMPO completely prevented the hydrazine-induced formation of megamitochondria in the liver, while it was partly prevented by allopurinol. The following changes observed in hydrazine-treated animals were improved almost completely by 4-OH-TEMPO:decreases in the body weight and liver weight; lowered rates of ADP-stimulated respiration and coupling efficiency of hepatic mitochondria; remarkable elevation of the level of lipid peroxidation. Improving effects of allopurinol were incomplete. The present results suggest that free radicals may play a key role in the mechanism of the hydrazine-induced formation of megamitochondria and that a part of free radicals generated during the hydrazine intoxication is ascribed to the degradation of purine nucleotides via xanthine oxidase. A general mechanism of the megamitochondria formation induced in various pathological conditions besides the case of hydrazine are discussed.

Allopurinol↗
PubMed1996

The three alpha 2-adrenergic receptor subtypes achieve basolateral localization in Madin-Darby canine kidney II cells via different targeting mechanisms.

The present studies examined the localization of the alpha2B- and alpha2C-adrenergic receptor (AR) subtypes in polarized Madin-Darby canine kidney cells (MDCK II) and the mechanisms by which this is achieved. Previously we demonstrated that the alpha2AAR subtype is directly delivered to lateral subdomain of MDCK II cells. Surface biotinylation strategies demonstrated that the alpha2BAR, like the alpha2AAR, achieves 85-90% basolateral localization at steady-state. However, in contrast to the alpha2AAR, this polarization occurs after initial random insertion of the alpha2BAR into both apical and basolateral surfaces followed by selective retention on the lateral subdomain (t1/2 the apical surface is 15-30 min; t1/2 the basolateral surface is 8-10 h). The alpha2CAR also is enriched on the basolateral surface at steady-state and, like the alpha2AAR, is directly delivered there. Morphological evaluation of the epitope-tagged alpha2AAR, alpha2BAR, and alpha2CAR subtypes by laser confocal microscopy not only corroborated the biochemically-defined basolateral localization of all three alpha2AR subtypes but also revealed that the alpha2CAR uniquely exists in an intracellular compartment(s) as well. Immunofluorescence due to intracellular alpha2CAR partially overlaps that due to calnexin, a marker for endoplasmic reticulum, as well as that due to mannosidase II, a marker for the trans-Golgi network. Taken together, the present findings demonstrate that the alpha2AAR, alpha2BAR, and alpha2CAR subtypes, which possess highly homologous structures and ultimately achieve similar polarization to the lateral surface of MDCK II cells, nonetheless manifest distinct trafficking itineraries.

Animals↗
PubMed1996

Traditional risk factors and ischemic stroke in young adults: the Baltimore-Washington Cooperative Young Stroke Study.

OBJECTIVE: To determine the association of hypertension, diabetes, and cigarette smoking with incidence of ischemic stroke in young adults. DESIGN: Case-control study. SETTING: Population-based sample of cases and controls. SUBJECTS: The study included 296 cases of incident ischemic stroke among black and white adults aged 18 to 44 years in central Maryland counties from the Baltimore-Washington Cooperative Young Stroke Study and 1220 black and white adults aged 18 to 44 years from the Maryland Behavioral Risk Factor Survey, a telephone survey of a random sample of the same region, to serve as controls. MAIN OUTCOME MEASURES: Logistic regression models were developed to determine the age-adjusted odds ratios for each risk factor. Population-attributable risk percent were computed based on the odds ratios and prevalence of each risk factor. RESULTS: The age-adjusted odds ratios (95% confidence intervals) for white men (WM), white women (WW), black men (BM), and black women (BW) were as follows: current cigarette smoking: WM, 2.0 (1.1-3.8), WW, 2.1 (1.1-4.3), BM, 3.3 (1.6-6.6), and BW, 2.2 (1.3-3.9); history of diabetes mellitus: WM, 22.9 (5.8-89.6), WW, 6.2 (1.9-20.2), BM, 4.2 (0.8-21.9), and BW, 3.3 (1.4-7.7); and history of hypertension: WM, 1.6 (0.7-3.2), WW, 2.5 (1.1-5.9), BM, 3.8 (1.8-7.9), and BW, 4.2 (2.4-7.5). The population-attributable risk percent (95% confidence intervals) were as follows: current cigarette smoking: WM, 22.6 (3.1-38.2), WW, 17.2 (4.0-34.0), BM, 40.5 (23.1-54.0), and BW, 29.1 (13.5-41.9); history of diabetes mellitus: WM, 19.0 (8.2-28.5), WW, 15.8 (3.8-26.3), BM, 13.2 (5.3-20.4), and BW, 22.1 (12.5-30.7); and history of hypertension: WM, 21.7 (6.2-34.6), WW, 21.3 (5.4-34.5), BM, 53.5 (39.0-64.4), and BW, 50.5 (37.1-61.1). CONCLUSIONS: Hypertension, diabetes mellitus, and current cigarette smoking are important risk factors in a biracial young adult population. Cigarette smoking and hypertension, the 2 most modifiable risk factors, were particularly important risk factors in young blacks.

Adolescent↗
PubMed1996

Mechanism of the formation of megamitochondria in the mouse liver induced by chloramphenicol.

Correlation between chloramphenicol-induced formation of megamitochondria in the mouse liver and oxidative stress was studied by lipid peroxidation analysis and electron microscopic technique. Chloramphenicol suppressed increases in the body weight and liver weight of experimental animals and at the same time induced a remarkable increase in lipid peroxidation in the liver during the formation of megamitochondria. A spin trapping agent, 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl, abolished all these changes induced by chloramphenicol. Namely, both the body weight and liver weight of chloramphenicol-treated animals stayed at the same levels as those of the control, and the formation of megamitochondria was completely suppressed. Allopurinol, a xanthine oxidase (EC 1.2.3.2) inhibitor, partly inhibited the changes induced by chloramphenicol, as described above. These results suggest that chloramphenicol-induced formation of megamitochondria is not simply ascribed to the suppression of the dividing process of mitochondria due to lowered protein synthesis in mitochondria but is intimately related to oxidative stress. Furthermore, the results obtained with allopurinol may indicate that enhanced levels of lipid peroxidation observed in chloramphenicol-treated animals are partly due to enhanced rate of the degradation of purine nucleotides catalyzed by xanthine oxidase.

Allopurinol↗
PubMed1995

Effects of indolinic and quinolinic aminoxyls on protein and lipid peroxidation of rat liver microsomes.

A study on peroxyl radical induced oxidation of rat liver microsomal membranes in the presence of different indolinic and quinolinic aminoxyls (Scheme 1) was carried out in order to test their efficiency as antioxidants in lipid and protein peroxidation. The extent of lipid peroxidation was quantified by the amount of malondialdehyde (MDA) produced, and the measurement of carbonyl residues was used as an index of microsomal protein oxidation. The results obtained suggest that lipid soluble indolinic and quinolinic aminoxyls are efficient in protecting lipids and proteins of biological membranes against oxidation. The efficacy of these aminoxyls as protectors of lipids and proteins was much higher than the water soluble TEMPOL. Moreover, the hydrophobic aminoxyls were more effective in preventing protein than lipid oxidation at low concentrations (1-20 microM). However, at high concentration (100 microM), lipid as opposed to protein oxidation was almost completely inhibited. The data supports the hypothesis that proteins probably have a different oxidation pattern from lipids.

Animals↗
PubMed1994

The effect of N-acyl ethanolamines on phosphatidylethanolamine phase transitions studied by laurdan generalised polarisation.

The effect of N-lauroylethanolamine (N-LEA) and N-oleoylethanolamine (N-OEA) on the thermal behaviour of fully hydrated egg phosphatidylethanolamine (TPE) was investigated by the steady-state fluorescence of 2-dimethylamino-(6-lauroyl)-naphtalene (laurdan) and 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). The parameter generalised polarisation (GP), calculated by exciting laurdan at 340 and 410 nm, revealed the gel to liquid crystalline lamellar (L alpha) as well as the L alpha to inverse hexagonal (HII) phase transitions of TPE. The L alpha to HII phase transition was not detected in TPE/N-OEA system, probably because of the formation of an intermediate Q224 cubic phase. The formation of Q224 phase in TPE/N-OEA and TPE/N-LEA systems was previously demonstrated by X-ray diffraction, but neither laurdan generalised polarisation nor TMA-DPH steady-state fluorescence anisotropy measurements revealed the presence of this phase. It is suggested that the lack of detection of the cubic phase is probably due to the similarity in dynamic characteristics and hydration levels of phospholipid headgroups in the bilayer and cubic phases.

2-Naphthylamine↗
PubMed1994

Isomeric and quaternary properties of homogenous 33 kDa protein from the venom of Chelonus near curvimaculatus.

The 33,000 Dalton venom protein of Chelonus near curvimaculatus was characterized for structural properties of charge, quaternary associations, and relationship to polydnavirus encoded proteins. Homogenous isoforms of the protein were isolated from the venom by sequential steps of 1) microdissection, 2) separation based on charge (Mono-Q column HPLC or narrow-range electrofocusing), and 3) centrifugal filtration based on molecular weight using Centricon microconcentrators. The purified protein dimerized under native conditions, and this quaternary association became denaturation resistant under certain conditions. Chemical modification of lysine epsilon amino groups did not disrupt such dimerization. The cDNA for the protein did not possess high similarity to any sequence encoded in the polydnavirus, as indicated by results of Southern blotting, but does possess similarity in its repeats to the repeats of the immunologically protective surface glycoprotein of Leishmania amazonensis.

Amino Acid Sequence↗
PubMed1994

Quinolinic aminoxyl protects albumin against peroxyl radical mediated damage.

A study of peroxyl radical-mediated bovine serum albumin oxidation in the presence of the quinolinic aminoxyl 1,2-dihydro-2,2-diphenyl-4-ethoxy-quinoline-1-oxyl (QAO) was carried out in order to test its efficiency as a protein antioxidant. Albumin oxidation was induced by the tert-butylhydroperoxide/PbO2 system. The extent of protein oxidation, measured by monitoring the formation of carbonyl groups, was considerably reduced in the presence of QAO. ESR measurements were carried out to confirm the consumption of the nitroxide during oxidation and its incorporation in the protein. The data obtained indicate that the quinolinic aminoxyl function can be used as an effective antioxidant in biological systems.

Antioxidants↗
PubMed1994

A sensitive detection of neutrophil activation by fluorescence quenching of membrane inserted singlet oxygen probe.

Fluorescence emission intensity of 1,3-diphenylisobenzofuran incorporated in polymorphonuclear granulocytes plasma membranes was investigated in basal conditions and during stimulation with different activators. Phorbol myristate acetate, known as the most effective "oxygen burst" inducer, produced a larger decrease in 1,3-diphenylisobenzofuran fluorescence intensity than 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activating factor) and N-formyl-methionyl-leucyl-phenylalanine, known as weak stimulants of oxygen uptake. Diphenyl iodonium an inhibitor of leukocyte NADPH oxidase, and the singlet oxygen selective trap alpha-terpinene inhibited the quenching effect of phorbol myristate acetate on 1,3-diphenylisobenzofuran fluorescence. These data suggest formation of singlet oxygen in activated leukocytes and demonstrate that measurement of 1,3-diphenylisobenzofuran fluorescence intensity provides a new sensitive method of detection of neutrophils activation.

Benzofurans↗
PubMed1993

N-acylethanolamines as membrane topological stress compromising agents.

The effect of different N-acylethanolamines on the phase behaviour of fully hydrated egg phosphatidylethanolamines is reported. In particular, in the presence of N-acylethanolamines, the transition from the liquid-crystalline lamellar (L alpha) to the inverse hexagonal (HII) phase is observed at higher temperature with respect to the temperature transition of pure phosphatidylethanolamine. Moreover, in correspondence of this transition, an intermediate Q224 (space group Pn3m) cubic phase has been detected. Since the structure of this cubic phase presents unique topological analogies with the lipid bilayer organization, these data suggest the possible role of N-acylethanolamines in stabilizing the biological membranes by avoiding a sudden change to a non-bilayer phase in those tissues which undergo stress conditions.

Calorimetry, Differential Scanning↗
PubMed1993

The interaction of phospholipid bilayers with pig heart AMP deaminase: Fourier-transform infrared spectroscopic and kinetic studies.

The interaction of pig heart AMP deaminase with different chemical species of phosphatidylcholine and with natural plasma membranes has been investigated. Phospholipids added to the system either as natural biological membranes (plasma membrane vesicles) or in the form of liposomes containing unsaturated phosphatidylcholine considerably enhanced AMP deaminase activity. The secondary structure of pig heart AMP deaminase in the absence and in the presence of dioleoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine liposomes was investigated by Fourier-transform infrared spectroscopy. Quantitative analysis of the amide I band showed that the enzyme contains 45% beta-sheets, 28% alpha-helix, 16% turns and 11% non-ordered structure. In the presence of dioleoyl phosphatidylcholine liposomes, the beta/alpha content ratio decreased; this decrease was dependent on the amount of lipid added. This phenomenon was not observed in the case of dipalmitoyl phosphatidylcholine liposomes. These data suggest a possible role for membrane phospholipids in the regulation of AMP deaminase activity.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

Characterization of two major isoforms of juvenile hormone esterase from Trichoplusia ni (Lepidoptera).

The two major isoforms of juvenile hormone (JH) esterase isolated from Trichoplusia ni were fragmented by cyanogen bromide and trypsin digestion. The resulting CNBr or CNBr/trypsin fragments were characterized and compared biochemically by SDS-PAGE, isoelectric focusing, two-dimensional electrophoresis and HPLC. Similar and unique fragments were examined for sequence, antigenic determinants and carbohydrate moieties. The studies identified small regions of the proteins which possess either potentially different sequences or different post-translational modifications. The location of a glycosylated asparagine residue was determined, as well as a region containing an epitope probably composed of a linear sequence of residues. An N-terminal region was identified that contained charge variation between the two isoforms and the sequence was obtained for the only unique CNBr/trypsin fragment detected from that region. These are the first data on mapping of regions of charge variation, epitope location and glycosylation sites for this enzyme from any insect species.

Amino Acid Sequence↗
PubMed1993

Effect of N-acylethanolamines with different acyl-chains on DPPC multilamellar liposomes.

The influence of N-acylethanolamines with different acyl-chains on the physico-chemical state of neutral phospholipids was investigated using dipalmitoyl phosphatidylcholine (DPPC) multilamellar liposomes. The thermal dependence of steady state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its charged derivative 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) was recorded. The N-acylethanolamines modified the DPPC phase transition temperature and broadened the transition temperature range in different ways depending on the N-acylethanolamines acyl chain characteristics. Our data suggest that the N-acylethanolamine acyl chain length and unsaturation play an important role in the interaction of these compounds with model membranes. The results show that long-chain-N-acylethanolamines interact largely with DPPC model membranes while a similar effect is not observed for the short ones.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

The cellular and physiological actions of insulin in the central nervous system.

Insulin is a peptide hormone involved in the regulation of glucose homeostasis. Its synthesis and function in the peripheral tissues have been extensively studied and well understood. In contrast, demonstration of insulin in the brain has raised questions concerning its origin and physiological significance. In spite of extensive studies, the source of insulin present in the brain has not yet been conclusively identified. Evidence exists in support of both peripheral and central origins of this hormone in the brain. Recognized physiological effects of insulin in the central nervous system (CNS) include regulation of food intake, control of glucose uptake and trophic actions on neuronal and glial cells. These actions of insulin are mediated by insulin receptor resembling closely that in peripheral tissues and coupled with tyrosine kinase signal transduction pathway. In this review we will discuss theories concerning the origin of insulin in the CNS. In addition, we will present current information on both cellular and physiological effects of this hormone in the brain.

Animals↗
PubMed1993

Indolinonic and quinolinic aminoxyls as protectants against oxidative stress.

A study on thermally and peroxyl radical induced oxidation of linolenic acid micelles in the presence of different concentrations of aminoxyls was carried out in order to test their efficiency as antioxidants in lipid peroxidation. The extent of peroxidation was measured by the malondialdehyde (MDA) produced and by oxygen consumption evaluated using an oxygraph. The results obtained indicate that indolinonic and quinolinic aminoxyls synthesized by us could be used as effective antioxidants in biological systems.

Antioxidants↗