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1.
J Nutr Health Aging ; 25(3): 340-346, 2021.
Article in English | MEDLINE | ID: mdl-33575726

ABSTRACT

IMPORTANCE: Altough disease-modifying factors such as malnutrition and diet have been associated with Alzheimer's disease (AD), little is known about the effects of pharmacological therapies on the nutritional status of AD patients. OBJECTIVE: To evaluate the nutritional status, prealbumin, and albumin serum levels and several anthropometric measurements in patients with probable moderate-stage AD, with and without rivastigmine drug treatment. STUDY DESIGN: A cross-sectional study. SETTING AND PARTICIPANTS: 34 patients were included, 17 with rivastigmine treatment and 17 without pharmacological treatment, over 60 years of both sexes. MEASUREMENTS: The nutritional status was evaluated using the Mini Nutritional Assessment (MNA). Albumin and prealbumin (transthyretin) levels and anthropometric evaluation were assessed using standard methods. RESULTS: A polarity of malnutrition was detected in the untreated group. According to the MNA survey, the risk of malnutrition is higher without rivastigmine treatment (p = 0.0001). There are a less loss of appetite, less psychological stress, greater mobility and independence in those patients receiving rivastigmine (p = 0.003, 0.008, 0.016 and 0.018, respectively). The body mass index does not show a statistical difference, however, categorizing it for older adults, this index was improved in those receiving rivastigmine (p = 0.016). The serum levels of albumin and prealbumin showed no significant statistical difference between the groups. CONCLUSION: Rivastigmine treatment shows a protective effect on malnutrition in patients with moderate-stage AD.


Subject(s)
Alzheimer Disease/physiopathology , Cholinesterase Inhibitors/therapeutic use , Malnutrition/complications , Nutrition Assessment , Nutritional Status/physiology , Rivastigmine/therapeutic use , Aged , Cholinesterase Inhibitors/pharmacology , Cross-Sectional Studies , Female , Humans , Male , Rivastigmine/pharmacology
2.
Biomed Pharmacother ; 129: 110485, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32768967

ABSTRACT

Sleep disorders are a widespread condition in patients with Parkinson's disease (PD), which has been linked to a deregulation of the circadian cycle and therefore of the clock genes. The aim of this study was to evaluate the effect of melatonin (MEL) on the PER1 and BMAL1 clock genes in patients with PD. A double-blind, cross-over, placebo-controlled randomized clinical trial pilot study was conducted in 26 patients with stage 1-3 PD according to the Hoehn & Yahr scale, who received either 25 mg of MEL or a placebo at noon and 30 min before bedtime for three months. The relative expression of the PER1 and BMAL1 genes was measured, as well as the presence of daytime, nocturnal, and global sleepiness, and the progression of PD. The levels of the PER1 and BMAL1 genes at baseline were 0.9 (0.1-3) vs. 0.56 (0.1-2.5), respectively; while after the intervention with MEL or placebo the BMAL1 levels increased to 2.5 (0-3.70) vs. 2.2 (0.10-3.30), respectively (d = 0.387). Fifty percent (50 %) of patients had daytime sleepiness and sixty-five percent (65 %) had abnormal nighttime sleepiness, yet neither group showed changes after the intervention. Patients with PD exhibited an alteration in the levels of the clock genes: MEL increased the levels of BMAL1, but the PER1 levels remained unchanged.


Subject(s)
ARNTL Transcription Factors/genetics , Melatonin/administration & dosage , Parkinson Disease/drug therapy , Period Circadian Proteins/genetics , Sleep Wake Disorders/drug therapy , ARNTL Transcription Factors/blood , Adult , Aged , Cross-Over Studies , Double-Blind Method , Female , Gene Expression Regulation , Humans , Male , Mexico , Middle Aged , Parkinson Disease/blood , Parkinson Disease/diagnosis , Parkinson Disease/genetics , Period Circadian Proteins/blood , Pilot Projects , Sleep Wake Disorders/blood , Sleep Wake Disorders/diagnosis , Sleep Wake Disorders/genetics , Time Factors , Treatment Outcome
3.
Gac Med Mex ; 153(Supl. 2): S72-S81, 2017.
Article in Spanish | MEDLINE | ID: mdl-29099102

ABSTRACT

Objective: To determine the effect of melatonin (MEL) administration on ciclooxigenase 2 (COX-2) activity and serum concentration of nitric oxide metabolites, lipoperoxides and glutathione peroxidase (GPx) activity in patients with Parkinson's disease. Methods: Prospective double-blind randomized clinical pilot trial. 13 patients were included and two groups were formed: MEL at doses of 25 mg orally every 12 hours for 12 months and placebo with corn starch. Patients were assessed using the Unified Parkinson's Disease Scale. A blood sample was taken at baseline and every 3 months until 12 months. Results: COX-2 activity decreased as did nitrates/nitrites (3, 6 and 9 months) and lipoperoxides (9 and 12 months); GPx exhibited no significant differences.


Subject(s)
Antioxidants/pharmacology , Cyclooxygenase 2/metabolism , Glutathione Peroxidase/blood , Lipid Peroxides/blood , Melatonin/pharmacology , Nitric Oxide/metabolism , Parkinson Disease/metabolism , Antioxidants/administration & dosage , Double-Blind Method , Humans , Melatonin/administration & dosage , Oxidative Stress , Pilot Projects , Prospective Studies
4.
Oxid Med Cell Longev ; 2013: 709493, 2013.
Article in English | MEDLINE | ID: mdl-23861993

ABSTRACT

UNLABELLED: Multiple sclerosis (MS) is a chronic inflammatory disease, which leads to focal plaques of demyelination and tissue injury in the central nervous system. Oxidative stress is also thought to promote tissue damage in multiple sclerosis. Current research findings suggest that omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapenta-enoic acid (EPA) and docosahexaenoic acid (DHA) contained in fish oil may have anti-inflammatory, antioxidant, and neuroprotective effects. The aim of the present work was to evaluate the efficacy of fish oil supplementation on serum proinflammatory cytokine levels, oxidative stress markers, and disease progression in MS. 50 patients with relapsing-remitting MS were enrolled. The experimental group received orally 4 g/day of fish oil for 12 months. The primary outcome was serum TNF α levels; secondary outcomes were IL-1 ß 1b, IL-6, nitric oxide catabolites, lipoperoxides, progression on the expanded disability status scale (EDSS), and annualized relapses rate (ARR). Fish oil treatment decreased the serum levels of TNF α , IL-1 ß , IL-6, and nitric oxide metabolites compared with placebo group (P ≤ 0.001). There was no significant difference in serum lipoperoxide levels during the study. No differences in EDSS and ARR were found. CONCLUSION: Fish oil supplementation is highly effective in reducing the levels of cytokines and nitric oxide catabolites in patients with relapsing-remitting MS.


Subject(s)
Interferon-beta/therapeutic use , Interleukin-1beta/blood , Interleukin-6/blood , Multiple Sclerosis/blood , Multiple Sclerosis/drug therapy , Oxidative Stress/drug effects , Tumor Necrosis Factor-alpha/blood , Adult , Animals , Female , Humans , Interferon beta-1b , Male
5.
Rev Esp Enferm Dig ; 102(6): 352-6, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20575594

ABSTRACT

BACKGROUND: Post-cholecystectomy bile duct injuries are identified by the onset of jaundice as well as elevated bilirubin and alkaline phosphatase levels during the peri-operative period. It is unknown how serum oxidative stress markers are modified in patients with post-cholecystectomy bile duct injuries. OBJECTIVE: To determine serum oxidative stress marker levels (lipid peroxidation by-products, nitrites/nitrates and total antioxidant capacity) in patients with post-cholecystectomy bile duct injuries. PATIENTS AND METHODS: A prospective, transversal and analytical study was designed with two groups. Group 1: 5 healthy volunteer subjects. Group 2: 52 patients with post-cholecystectomy bile duct injuries (43 female and 9 male). An elective bilio-digestive reconstruction was performed at week 8. The serum oxidative stress marker levels were quantified by colorimetric method. RESULTS: Patients with bile duct injuries had a significant increased serum lipid peroxides (malondialdehyde and 4-hydroxy-alkenals) and nitric oxide metabolites (nitrites/nitrates) levels compared to the control group. In contrast, total antioxidant capacity in patients with bile duct injuries remained similar compared to healthy controls. CONCLUSIONS: The results show that oxidative stress is usually associated to bile duct injury.


Subject(s)
Bile Ducts/injuries , Bile Ducts/metabolism , Cholecystectomy , Oxidative Stress , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Prospective Studies
6.
Rev. esp. enferm. dig ; 102(6): 352-356, jun. 2010. ilus, tab
Article in Spanish | IBECS | ID: ibc-79853

ABSTRACT

Introducción: las lesiones de las vías biliares postcolecistectomíase establecen por la aparición de ictericia, elevación de las bilirrubinasy de la fosfatasa alcalina durante el periodo perioperatorio.Se desconoce cómo se modifican los marcadores de estrésoxidativo en el suero de los pacientes con lesiones de las vías biliarespostcolecistectomía.Objetivo: determinar los marcadores de estrés oxidativo (productosde peroxidación de lípidos, catabolitos del óxido nítrico ycapacidad antioxidante total) en el suero de pacientes con lesionesde las vías biliares.Pacientes y métodos: se realizó un estudio prospectivotransversal analítico. Se formaron 2 grupos de estudio. Grupo 1:5 voluntarios sanos que sirvieron como control. Grupo 2: 52 pacientescon lesiones de las vías biliares postcolecistectomía (43 femeninosy 9 masculinos). La reconstrucción bilio-digestiva se realizóde manera electiva a las 8 semanas. Los niveles séricos de losmarcadores de estrés oxidativo se cuantificaron mediante métodoscolorimétricos.Resultados: los niveles séricos de los productos de peroxidaciónde lípidos (malondialdehído y 4-hidroxialquenos) y de los catabolitosdel óxido nítrico (nitritos/nitratos) aumentaron significativamenteen los pacientes con lesiones de las vías biliares encomparación a los voluntarios sanos. En contraste, la capacidadantioxidante total en el suero de los pacientes con lesiones de lasvías biliares fue similar a la de los voluntarios sanos.Conclusiones: los resultados muestran que el estrés oxidativoen suero es un componente que se asocia a las lesiones de las víasbiliares(AU)


Background: post-cholecystectomy bile duct injuries are identified by the onset of jaundice as well as elevated bilirubin and alkaline phosphatase levels during the peri-operative period. It is unknown how serum oxidative stress markers are modified in patients with post-cholecystectomy bile duct injuries. Objective: to determine serum oxidative stress marker levels (lipid peroxidation by-products, nitrites/nitrates and total antioxidant capacity) in patients with post-cholecystectomy bile duct injuries. Patients and methods: a prospective, transversal and analytical study was designed with two groups. Group 1: 5 healthy volunteer subjects. Group 2: 52 patients with post-cholecystectomy bile duct injuries (43 female and 9 male). An elective bilio-digestive reconstruction was performed at week 8. The serum oxidative stress marker levels were quantified by colorimetric method. Results: patients with bile duct injuries had a significant increased serum lipid peroxides (malondialdehyde and 4-hydroxy-alkenals) and nitric oxide metabolites (nitrites/nitrates) levels compared to the control group. In contrast, total antioxidant capacity in patients with bile duct injuries remained similar compared to healthy controls. Conclusions: the results show that oxidative stress is usually associated to bile duct injury(AU)


Subject(s)
Humans , Male , Female , Oxidative Stress , Oxidative Stress/physiology , Bile Duct Diseases/complications , Bile Duct Diseases/diagnosis , Bile Ducts/injuries , Serum , Serum/physiology , Cholecystectomy/methods , Prospective Studies , Cross-Sectional Studies
7.
Anat Histol Embryol ; 38(4): 279-81, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19614629

ABSTRACT

The ultrastructure of the Harderian gland of Atlantic bottlenose dolphin (Tursiops truncatus) was examined by scanning electron microscopy (SEM). We found the following surface features: the typical round appearance of the ascinar glandular unit with a finely granular surface, a thin cortex and immediately below two types of cells: type I cells (characterized by small lipid vacuoles) and type II cells (characterized by large lipid vacuoles). It has been suggested that different cells forms represent a single cell type in varying activity states. Additionally, a coalescent tubular complex, a small balloon-like structures and large globular structures were observed. These structures may be reservoirs of secretion products.


Subject(s)
Bottle-Nosed Dolphin/anatomy & histology , Harderian Gland/ultrastructure , Animals , Male , Microscopy, Electron, Scanning/veterinary , Orbit/anatomy & histology , Orbit/ultrastructure
8.
Dis Markers ; 24(3): 151-6, 2008.
Article in English | MEDLINE | ID: mdl-18334736

ABSTRACT

It has been suggested that mitochondrial dysfunction and defects in membrane structure could be implied in AD pathogenesis. The aim of the present work was the study of membrane fluidity in submitochondrial platelet particles and erythrocyte membranes from Mexican patients. Blood samples were obtained from 30 patients with Alzheimer disease and 30 aged-matched control subjects. Membrane fluidity determinations were done using a very low concentration of the fluorescent dipyrenylpropane probe incorporated in both types of membranes. This probe is able to give excimer and monomer fluorescence, therefore it can be used to monitor fluidity changes in biological membranes. The data obtained showed that in submitochondrial particles from AD patients, the excimer to monomer fluorescent intensity ratio was lower (0.231 +/- 0.008) than aged-matched control subjects (0.363 +/- 0.014). Therefore, membrane fluidity was lower in AD samples. On the other hand, we found similar membrane fluidity in erythrocytes from AD patients and aged-matched controls: the fluorescent intensity ratios were 0.312 +/- 0.03 and 0.305 +/- 0.033, respectively. In addition, lipid peroxidation in submitochondrial particles and erythrocyte membranes was higher in AD samples than in aged-matched controls. These data suggest that submitochondrial platelet particles are more sensitive to oxidative stress than erythrocyte membranes.


Subject(s)
Alzheimer Disease/blood , Blood Platelets/ultrastructure , Erythrocyte Membrane/ultrastructure , Membrane Fluidity , Pyrenes/metabolism , Submitochondrial Particles , Humans , Lipid Peroxidation , Mexico
9.
Dis Markers ; 22(3): 119-25, 2006.
Article in English | MEDLINE | ID: mdl-16788245

ABSTRACT

OBJECTIVE: To determine the beta-amyloid precursor protein (betaAPP) isoforms ratio as a risk factor for Alzheimer's Disease and to assess its relationship with demographic and genetic variables of the disease. METHODS: Blood samples from 26 patients fulfilling NINCDS-ADRDA diagnostic criteria for AD and 46 healthy control subjects were collected for Western blotting for betaAPP. A ratio of betaAPP isoforms, in optical densities, between the upper band (130 Kd) and the lower bands (106-110 Kd) was obtained. Odds ratios were obtained to determine risk factor of this component. RESULTS: betaAPP ratio on AD subjects was lower than that of control subjects: 0.3662 +/- 0.1891 vs. 0.6769 +/- 0.1021 (mean +/- SD, p<0.05). A low betaAPP ratio (<0.6) showed an OR of 4.63 (95% CI 1.45-15.33). When onset of disease was taken into account, a betaAPP ratio on EOAD subjects of 0.3965 +/- 0.1916 was found vs. 0.3445 +/- 0.1965 on LOAD subjects (p>0.05). CONCLUSIONS: Altered betaAPP isoforms is a high risk factor for Alzheimer's disease, although it has no influence on the time of onset of the disease.


Subject(s)
Alzheimer Disease/diagnosis , Amyloid beta-Protein Precursor/blood , Aged , Alleles , Amyloid beta-Peptides/blood , Apolipoproteins E/genetics , Blotting, Western , Early Diagnosis , Female , Humans , Male , Mexico , Middle Aged , Polymorphism, Genetic , Protein Isoforms/blood
10.
Biomed Pharmacother ; 60(2): 86-91, 2006 Feb.
Article in English | MEDLINE | ID: mdl-16488110

ABSTRACT

It has been demonstrated that high concentrations of monosodium glutamate in the central nervous system induce neuronal necrosis and damage in retina and circumventricular organs. In this model, the monosodium glutamate is used to induce an epileptic state; one that requires highly concentrated doses. The purpose of this study was to evaluate the toxic effects of the monosodium glutamate in liver and kidney after an intra-peritoneal injection. For the experiment, we used 192 Wistar rats to carry out the following assessments: a) the quantification of the enzymes alanine aminotransferase and aspartate aminotransferase, b) the quantification of the lipid peroxidation products and c) the morphological evaluation of the liver and kidney. During the experiment, all of these assessments were carried out at 0, 15, 30 and 45 min after the intra-peritoneal injection. In the rats that received monosodium glutamate, we observed increments in the concentration of alanine aminotransferase and aspartate aminotransferase at 30 and 45 min. Also, an increment of the lipid peroxidation products, in kidney, was exhibited at 15, 30 and 45 min while in liver it was observed at 30 and 45 min. Degenerative changes were observed (edema-degeneration-necrosis) at 15, 30 and 45 min.


Subject(s)
Chemical and Drug Induced Liver Injury/enzymology , Food Additives/toxicity , Kidney Diseases/chemically induced , Sodium Glutamate/toxicity , Animals , Chemical and Drug Induced Liver Injury/metabolism , Chemical and Drug Induced Liver Injury/pathology , Injections, Intraperitoneal , Kidney Diseases/pathology , Lipid Peroxidation/drug effects , Liver Function Tests , Male , Rats , Rats, Wistar
11.
Rev Neurol ; 40(2): 81-5, 2005.
Article in Spanish | MEDLINE | ID: mdl-15712160

ABSTRACT

INTRODUCTION: Recent studies indicate that decreased energy generation by mitochondria is a feature that is common across neurodegenerative diseases. PATIENTS AND METHODS: In order to obtain direct evidence that mitochondrial functioning is altered, we measured the hydrolytic activity of F0F1-ATPase and its capacity to generate a stable proton gradient in submitochondrial particles in 29 patients diagnosed with probable Alzheimer's disease (AD). Submitochondrial particles were obtained from platelets of patients with a diagnosis of probable AD and from clinically healthy controls. RESULTS: Data revealed that the hydrolytic activity of F0F1-ATPase increases significantly in patients with probable AD (41.7+/-4.3 nmol PO4 min-1[mg protein]-1, n=29) as compared to the control subjects (29.1+/-1.9 nmol PO4 min-1 [mg protein]-1, n=29). It is important to note that, in the male population with probable AD, we found that hydrolytic activity of F0F1-ATPase increased as cerebral deterioration progressed. We also detected a lower pH gradient in the submitochondrial particles of patients with probable AD (0.28+/-0.08 pH units, n=25) as compared to the controls (0.5+/-0.1 pH units, n=20). CONCLUSIONS: Overall, these data point to an alteration in the functioning of the enzyme.


Subject(s)
Alzheimer Disease/enzymology , Alzheimer Disease/physiopathology , Blood Platelets/enzymology , Proton-Translocating ATPases/metabolism , Submitochondrial Particles/enzymology , Alzheimer Disease/blood , Alzheimer Disease/diagnosis , Blood Platelets/cytology , Disease Progression , Female , Humans , Hydrogen-Ion Concentration , Male
12.
Rev. neurol. (Ed. impr.) ; 40(2): 81-85, 16 ene., 2005. graf
Article in Es | IBECS | ID: ibc-037112

ABSTRACT

Introducción. Los estudios recientes indican que una disminución en la generación de energía de la mitocondria es una característica que unifica a las enfermedades neurodegenerativas. Pacientes y métodos. Para obtener evidencia directa que la función mitocondrial se altera, cuantificamos en 29 pacientes diagnosticados con probable enfermedad de Alzheimer (EA) la actividad hidrolítica de la F0F1-ATPasa y su capacidad para generar un gradiente estable de protones en partículas submitocondriales. Las partículas submitocondriales se obtuvieron de plaquetas de pacientes con diagnóstico probable de EA y de controles clínicamente sanos. Resultados. Los datos revelaron que la actividad hidrolítica de la F0F1-ATPasa se incrementa de manera significativa en los pacientes con la probable EA -41,7 ± 4,3 nmol PO4 min-1(mg proteína)-1, con n = 29- en comparación con los controles -29,1 ± 1,9 nmol PO4 min-1 (mg proteína)- 1, con n = 29-. De manera importante, encontramos que en la población masculina con probable EA, la actividad hidrolítica de la F0F1-ATPasa aumenta conforme progresa el deterioro cerebral. También detectamos un gradiente de pH menor en las partículas submitocondriales de los pacientes con probable EA (0,28 ± 0,08 unidades de pH, n = 25) comparados con los controles (0,5 ± 0,1 unidades de pH, n = 20). Conclusión. Estos datos, en conjunto, indican una alteración funcional en la enzima


Introduction. Recent studies indicate that decreased energy generation by mitochondria is a feature that is common across neurodegenerative diseases. Patients and methods. In order to obtain direct evidence that mitochondrial functioning is altered, we measured the hydrolytic activity of F0F1-ATPase and its capacity to generate a stable proton gradient in submitochondrial particles in 29 patients diagnosed with probable Alzheimer’s disease (AD). Submitochondrial particles were obtained from platelets of patients with a diagnosis of probable AD and from clinically healthy controls. Results. Data revealed that the hydrolytic activity of F0F1-ATPase increases significantly in patients with probable AD (41.7 ± 4.3 nmol PO4 min-1[mg protein]-1, n = 29) as compared to the control subjects (29.1 ± 1.9 nmol PO4 min-1 [mg protein]-1, n = 29). It is important to note that, in the male population with probable AD, we found that hydrolytic activity of F0F1-ATPase increased as cerebral deterioration progressed. We also detected a lower pH gradient in the submitochondrial particles of patients with probable AD (0.28 ± 0.08 pH units, n = 25) as compared to the controls (0.5 ± 0.1 pH units, n = 20). Conclusions. Overall, these data point to an alteration in the functioning of the enzyme


Subject(s)
Male , Female , Humans , Alzheimer Disease/diagnosis , Proton-Translocating ATPases/physiology , Submitochondrial Particles/physiology , Hydrolysis , Adenosine Triphosphate/physiology , Electron Transport Complex IV/physiology
13.
Biochim Biophys Acta ; 1457(3): 200-10, 2000 Apr 21.
Article in English | MEDLINE | ID: mdl-10773165

ABSTRACT

The effect of antimycin, myxothiazol, 2-heptyl-4-hydroxyquinoline-N-oxide, stigmatellin and cyanide on respiration, ATP synthesis, cytochrome c reductase, and membrane potential in mitochondria isolated from dark-grown Euglena cells was determined. With L-lactate as substrate, ATP synthesis was partially inhibited by antimycin, but the other four inhibitors completely abolished the process. Cyanide also inhibited the antimycin-resistant ATP synthesis. Membrane potential was collapsed (<60 mV) by cyanide and stigmatellin. However, in the presence of antimycin, a H(+)60 mV) that sufficed to drive ATP synthesis remained. Cytochrome c reductase, with L-lactate as donor, was diminished by antimycin and myxothiazol. Cytochrome bc(1) complex activity was fully inhibited by antimycin, but it was resistant to myxothiazol. Stigmatellin inhibited both L-lactate-dependent cytochrome c reductase and cytochrome bc(1) complex activities. Respiration was partially inhibited by the five inhibitors. The cyanide-resistant respiration was strongly inhibited by diphenylamine, n-propyl-gallate, salicylhydroxamic acid and disulfiram. Based on these results, a model of the respiratory chain of Euglena mitochondria is proposed, in which a quinol-cytochrome c oxidoreductase resistant to antimycin, and a quinol oxidase resistant to antimycin and cyanide are included.


Subject(s)
Euglena/metabolism , Mitochondria/metabolism , Adenosine Triphosphate/biosynthesis , Animals , Antimycin A/analogs & derivatives , Antimycin A/pharmacology , Cell Respiration/drug effects , Enzyme Activation/drug effects , Lactic Acid/metabolism , Methacrylates , NADH Dehydrogenase/metabolism , Oxidative Phosphorylation/drug effects , Polyenes/pharmacology , Sodium Cyanide/pharmacology , Thiazoles/pharmacology
14.
Eur J Biochem ; 267(4): 993-1000, 2000 Feb.
Article in English | MEDLINE | ID: mdl-10672007

ABSTRACT

Activation of the latent ATPase activity of inside-out vesicles from plasma membranes of Paracoccus denitrificans was studied. Several factors were found to induce activation: heat, membrane energization by succinate oxidation, methanol, oxyanions (sulfite, phosphate, arsenate, bicarbonate) and limited proteolysis with trypsin. Among the oxyanions, sulfite induced the higher increase in ATPase activity. Sulfite functioned as a nonessential activator that slightly modified the affinity for ATP and increased notoriously the Vmax. There was a competitive effect between sulfite, bicarbonate and phosphate for ATPase activation; their similar chemical geometry suggests that these oxyanions have a common binding site on the enzyme. Dithiothreitol did not affect the ATPase activity. ATPase activation by sulfite was decreased by uncoupler, enhanced by trypsin and inhibited by ADP, oligomycin and venturicidin. In contrast, activation induced by succinate was less sensitive to ADP, oligomycin, venturicidin and trypsin. It is proposed that the active states induced by sulfite and succinate reflect two conformations of the enzyme, in which the inhibitory subunit epsilon is differently exposed to trypsin.


Subject(s)
Cell Membrane/metabolism , Energy Metabolism , Paracoccus denitrificans/enzymology , Proton-Translocating ATPases/metabolism , Sulfites/pharmacology , Adenosine Diphosphate/metabolism , Adenosine Diphosphate/pharmacology , Adenosine Triphosphate/metabolism , Anions/metabolism , Anions/pharmacology , Bicarbonates/metabolism , Bicarbonates/pharmacology , Binding Sites , Cell Membrane/drug effects , Cell Membrane/enzymology , Energy Metabolism/drug effects , Enzyme Activation/drug effects , Hot Temperature , Hydrogen-Ion Concentration , Hydrolysis/drug effects , Kinetics , Methanol/metabolism , Methanol/pharmacology , Paracoccus denitrificans/cytology , Phosphates/metabolism , Phosphates/pharmacology , Proton-Translocating ATPases/antagonists & inhibitors , Succinic Acid/metabolism , Succinic Acid/pharmacology , Sulfites/antagonists & inhibitors , Sulfites/metabolism , Trypsin/metabolism , Trypsin/pharmacology , Uncoupling Agents/metabolism , Uncoupling Agents/pharmacology
15.
Plant Physiol ; 114(3): 1095-101, 1997 Jul.
Article in English | MEDLINE | ID: mdl-9232885

ABSTRACT

Maize (Zes mays L.) embryos, isolated from the developing seed and incubated in dilute buffer, show reduced triacylglycerol (TAG) synthesis, and accumulation stops after 24 h. Synthesis and accumulation can be maintained at high levels if the incubation medium contains abscisic acid (ABA) and/or a high osmotic concentration. Radiolabeled free fatty acids accumulate at higher levels in embryos that contain less TAG, and acetyl coenzyme A carboxylase activity remains essentially unchanged under all of the conditions tested. In contrast, the activities of the acyltransferases required for TAG synthesis remain high only in embryos incubated with ABA and/or a high osmotic concentration. Dose-response curves showed that 4 microM of ABA or mannitol at -1.0 MPa elicits a full response; both values are within the range considered to be physiological. The TAG synthesis capacity and discylglycerol acyltransferase activity lost by pretreatment of the embryos can be restored by re-exposure to ABA or high osmoticum. Germination is not involved because isolated scutellum halves showed the same changes in enzyme activity found in the whole embryo but did not germinate. Our results provide direct evidence for the regulation of TAG-synthesizing activities in maize embryos by ABA and the osmotic potential of the environment.


Subject(s)
Abscisic Acid/pharmacology , Acyltransferases/metabolism , Seeds/enzymology , Zea mays/enzymology , Acetyl-CoA Carboxylase/metabolism , Diacylglycerol O-Acyltransferase , Fatty Acids, Nonesterified/metabolism , Kinetics , Mannitol/pharmacology , Osmolar Concentration , Seeds/drug effects , Time Factors , Triglycerides/metabolism , Zea mays/drug effects
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