RESUMEN

AIMS/HYPOTHESIS: Islet amyloid deposits are present in over 85% of Type 2 diabetic patients and have been suggested to be pathogenic. The mechanism that converts islet amyloid polypeptide (IAPP), the unique component of these deposits, into amyloid fibrils in vivo is not known. The amino acid sequence of IAPP is critical but insufficient for beta-pleated sheet formation. As apolipoprotein E (apoE), another component of islet amyloid deposits, plays a critical role in amyloid formation in Alzheimer's disease, we hypothesised that apoE could play an important role in islet amyloid formation. METHODS: Transgenic mice expressing the human form of IAPP ( hIAPP (+/0)) were crossbred with apoE deficient ( apoE (-/-)) mice and followed for 12 months, at which time the prevalence and severity of islet amyloid, as well as plasma glucose, hIAPP, immunoreactive insulin (IRI) and lipid concentrations were measured. RESULTS: The prevalence and severity of islet amyloid after one year of follow up were comparable among hIAPP (+/0) mice that were apoE (+/+), apoE (+/-) or apoE (-/-). Differences in glucose tolerance, lipid abnormalities or changes in pancreatic content or plasma concentrations of hIAPP and/or IRI did not account for these findings. CONCLUSION/INTERPRETATION: Our data shows that, unlike in the localized amyloidosis in the brain characteristic of Alzheimer's disease, apoE is not critical for islet amyloid formation in a transgenic mouse model of Type 2 diabetes mellitus. These results indicate that the mechanisms of localised amyloid formation probably vary among different amyloid-associated disorders. Therefore, therapeutic strategies targeting apoE might not apply equally to patients with different amyloid associated diseases.

Asunto(s)

Amiloide/metabolismo , Apolipoproteínas E/deficiencia , Islotes Pancreáticos/metabolismo , Amiloide/genética , Animales , Apolipoproteínas E/genética , Quimera , Genotipo , Intolerancia a la Glucosa , Humanos , Polipéptido Amiloide de los Islotes Pancreáticos , Metabolismo de los Lípidos , Ratones , Ratones Endogámicos , Ratones Noqueados/genética , Ratones Transgénicos/genética

RESUMEN

We hypothesized that plasma extracellular superoxide dismutase (EC-SOD) activity reflects the zinc nutriture of healthy pregnant women. Sixty-three women were selected from 580 African-American women who participated in a clinical trial to evaluate the effect of prenatal zinc supplementation on pregnancy outcome. Half of the women received zinc (25 mg/d) and the other half was given a placebo from about 19 wk gestation to delivery. In the trial, a positive effect of zinc supplementation on birthweight was observed, indicating that the population as a whole had suboptimal zinc nutriture. Using plasma samples obtained during the trial, EC-SOD activities were measured and the values were compared with plasma zinc concentrations and plasma alkaline phosphatase activities. Plasma EC-SOD activities in our subjects were lower than previously published values for healthy adults in Korea. Although plasma EC-SOD activity may reflect severe zinc deficiency, it is not a sensitive marker for marginal deficiency status. Plasma EC-SOD activities did not prove to be a better indicator of zinc nutriture of pregnant women than either plasma zinc or plasma alkaline phosphatase activities.

Asunto(s)

Embarazo/sangre , Superóxido Dismutasa/sangre , Zinc/administración & dosificación , Fosfatasa Alcalina/sangre , Cobre/sangre , Método Doble Ciego , Espacio Extracelular/enzimología , Femenino , Humanos , Micronutrientes/administración & dosificación , Necesidades Nutricionales , Resultado del Embarazo , Zinc/sangre

RESUMEN

Lipoprotein retention by vascular extracellular matrix proteoglycans is important in atherogenesis. Proteoglycans bind apolipoprotein (apo)B- and apoE-containing lipoproteins. However, the colocalization of apoA-I and apoE with biglycan in atherosclerotic lesions suggests that vascular proteoglycans also may trap high density lipoproteins (HDLs). Because the major HDL subclasses may be atheroprotective to different degrees, we investigated the role of apoE in mediating HDL(2) and HDL(3) binding to the extracellular vascular proteoglycan, biglycan. ApoE-free HDL(2) and HDL(3) did not bind to purified [(35)S]SO(4)-biglycan, whereas apoE-containing HDL(2) and HDL(3) (HDL+E) did. The extent of binding correlated positively with the apoE content for both HDL(2) and HDL(3), although HDL(2)+E had a 3.5-fold higher affinity than did HDL(3)+E. ApoE on HDL(3) was cleaved into 22- and 12-kDa fragments, whereas apoE on HDL(2) remained intact. These results suggest that the cleaved apoE on HDL(3) results in diminished biglycan binding of HDL(3)+E relative to HDL(2)+E. Reducing positive charges on lysine and arginine residues on HDL+E eliminated biglycan binding, suggesting an ionic interaction. Thus, apoE is an important determinant of HDL binding to extracellular vascular proteoglycans and may play a role in HDL retention in the artery wall.

Asunto(s)

Apolipoproteínas E/fisiología , HDL-Colesterol/metabolismo , Proteoglicanos/metabolismo , Apolipoproteína A-I/metabolismo , Arteriosclerosis/metabolismo , Biglicano , Vasos Coronarios/metabolismo , Proteínas de la Matriz Extracelular/metabolismo , Espacio Extracelular/metabolismo , Humanos , Músculo Liso Vascular/metabolismo , Unión Proteica/fisiología

RESUMEN

Retention of low density lipoproteins (LDL) by vascular proteoglycans and their subsequent oxidation are important in atherogenesis. Lipoprotein lipase (LPL) can bind LDL and proteoglycans, although the effect of different proteoglycans to influence the ability of LPL to act as a bridge in the formation of LDL-proteoglycan complexes is unknown. Using an electrophoretic gel mobility shift assay, [(35)S]SO(4)-labeled versican and biglycan, two extracellular proteoglycans secreted by vascular cells, bound native LDL in a saturable fashion. The addition of bovine milk LPL dose-dependently increased the binding of native LDL to both versican and biglycan, approaching saturation at 30-40 microgram/ml LPL for versican and 20 microgram/ml LPL for biglycan. LDL was oxidized by several methods, including copper, 2, 2-azo-bis(2-amidinopropane)-2HCl and hypochlorite. Extensively copper- and hypochlorite-oxidized LDL bound poorly to versican and biglycan. Proteoglycan binding to LDL was correlated inversely with the extent of LDL; however, the addition of LPL to oxidized LDL together with biglycan or versican allowed the oxidized LDL to bind the proteoglycans in an LPL dose-dependent manner. Addition of LPL had a greater relative effect on the binding of extensively oxidized LDL to proteoglycans compared with native LDL. LPL had a slightly greater effect on increasing the binding of native and oxidized LDL to biglycan than versican. Thus, LPL in the artery wall might increase the atherogenicity of oxidized LDL, since it enables its binding to vascular biglycan and versican.

Asunto(s)

Arterias/metabolismo , Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Lipoproteína Lipasa/farmacología , Lipoproteínas LDL/metabolismo , Músculo Liso Vascular/metabolismo , Proteoglicanos/metabolismo , Animales , Biglicano , Bovinos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Proteínas de la Matriz Extracelular , Humanos , Cinética , Lectinas Tipo C , Proteínas de la Leche/metabolismo , Oxidación-Reducción , Unión Proteica/efectos de los fármacos , Versicanos

RESUMEN

BACKGROUND: Because the content of specific proteoglycans and apolipoproteins is increased in atherosclerotic plaques and in vitro studies have suggested a role for proteoglycans in mediating plaque apolipoprotein (apo) retention, immunohistochemistry was performed to systematically examine the relative locations of proteoglycans and apolipoproteins in human atherosclerosis. METHODS AND RESULTS: The spatial relationships of versican, biglycan, and apoE were compared on 68 human coronary artery segments; apoA-I and apoB also were evaluated on an additional 20 segments. Nonatherosclerotic intima contained extensive deposits of versican, whereas deposits of apoE, apoB, and apoA-I were much less prevalent. In contrast, nearly all atherosclerotic segments contained substantial deposits of biglycan, apoE, apoA-I, and apoB. There was a high degree of colocalization of apoE and biglycan deposits. ApoA-I, the major apolipoprotein of HDL, and apoB also were detected in regions with apoE and biglycan deposition. Exceptions to the localization of biglycan with apolipoproteins were found in regions that lacked intact extracellular matrix because of necrosis or dense macrophage accumulation. In vitro studies demonstrated that biglycan binds apoE-containing but not apoE-free HDL and that biglycan also binds LDL. CONCLUSIONS: These results suggest that biglycan may bind apoE and apoB in atherosclerotic intima. They also raise the possibility that apoE may act as a "bridging" molecule that traps apoA-I-containing HDL in atherosclerotic intima. Taken together, these findings are consistent with the hypothesis that biglycan may contribute to the pathogenesis of atherosclerosis by trapping lipoproteins in the artery wall.

Asunto(s)

Apolipoproteínas/metabolismo , Enfermedad de la Arteria Coronaria/metabolismo , Vasos Coronarios/metabolismo , Proteoglicanos/metabolismo , Apolipoproteína A-I/metabolismo , Apolipoproteínas B/metabolismo , Apolipoproteínas E/metabolismo , Biglicano , Enfermedad de la Arteria Coronaria/patología , Vasos Coronarios/patología , Proteínas de la Matriz Extracelular , Humanos , Inmunohistoquímica , Macrófagos/patología , Necrosis , Distribución Tisular

RESUMEN

This study evaluated whether human monocyte-derived macrophages synthesize specific types of proteoglycans with lipoprotein-binding capability that could contribute to lipid retention in the arterial wall. After labeling with either [35S]SO4 or [35S]methionine, macrophages secreted a high molecular mass proteoglycan, with glycosaminoglycan chains of approximately 18 kDa and core protein bands of approximately 100 and 55 kDa. Both core protein bands were recognized by an antibody to PG-100, an antibody that recognizes the proteoglycan form of macrophage colony-stimulating factor (PG-100/PG-MCSF). The interaction between PG-100/PG-MCSF and low density lipoproteins (LDL) was examined by gel mobility shift. In this system, PG-100/PG-MCSF was resolved further into two forms. The two forms had the same core proteins but differed in their overall size and glycosaminoglycan content. The larger form contained glycosaminoglycan chains that were entirely chondroitin ABC lyase-sensitive, whereas the smaller form contained chains that were sensitive to both chondroitin ABC lyase and heparinase. Both forms bound native LDL with high affinity, but the larger form bound LDL with higher affinity than the smaller form. The glycosaminoglycan chains of PG-100/PG-MCSF, but not the core proteins, were responsible for binding to native LDL. Mildly oxidized LDL and methyl-LDL, which have an electrophoretic charge similar to that of native LDL, also bound PG-100/PG-MCSF. In contrast, extensively oxidized LDL and acetyl-LDL, which are more electronegative than native LDL, did not bind to either form of PG-100/PG-MCSF. The demonstration of two forms of human monocyte-derived macrophage PG-100/PG-MCSF which bind LDL may represent an additional role for macrophages in the extracellular trapping of lipoproteins in atherosclerosis.

Asunto(s)

Lipoproteínas LDL/metabolismo , Factor Estimulante de Colonias de Macrófagos/metabolismo , Macrófagos/metabolismo , Monocitos/metabolismo , Proteoglicanos/metabolismo , Células Cultivadas , Condroitina ABC Liasa/metabolismo , Cromatografía por Intercambio Iónico , Heparitina Sulfato/metabolismo , Humanos , Peso Molecular

RESUMEN

Previous studies have demonstrated that zinc deficiency can be associated with high rates of oxidative damage to testes lipids, proteins, and DNA in male rats. In the present work, different aspects of the oxidant defense system (enzymes and lipid-soluble antioxidant substances) were characterized in the testes of control and zinc-deficient rats. Seventeen-day-old males were given free access to either a control (25 microg Zn/g) or a zinc-deficient (0.5 microg Zn/g) diet, or the 25 microg Zn/g diet at a level of food intake similar to that of zinc-deficient rats. Animals were sacrificed 14 days after the initiation of the diet. The activities of copper-zinc superoxide dismutase (CuZn SOD) and glutathione reductase (GRed) were significantly higher (34% and 23%, respectively) in testes from the zinc-deficient animals than in those of the ad libitum controls. In testes, the activities of manganese superoxide dismutase (Mn SOD) and glutathione peroxidase (GPx), and the concentration of alpha-tocopherol and ubiquinol-9 and -10 were similar among the groups. However, the ratio of reduced/total concentration of both ubiquinols was higher in the zinc-deficient and restrict-fed animals than in the ad libitum controls. Testes homogenates from the zinc-deficient rats showed a low susceptibility to Fe(II)-induced oxidation, which could be explained in part by a lower peroxidation index, mainly due to the decreased testicular content of the fatty acid 20:4 observed in these animals. In summary, both undernutrition and zinc-deficiency can cause an oxidative stress situation in testes, for which cells tend to compensate by increasing select components of the oxidant defense system.

Asunto(s)

Estrés Oxidativo/fisiología , Oxidorreductasas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Testículo/metabolismo , Zinc/deficiencia , Animales , Peso Corporal , Cobre/sangre , Glutatión Peroxidasa/metabolismo , Glutatión Reductasa/metabolismo , Masculino , Tamaño de los Órganos , Fosfolípidos/análisis , Ratas , Ratas Sprague-Dawley , Superóxido Dismutasa/metabolismo , Testículo/enzimología , Testículo/patología , Sustancias Reactivas al Ácido Tiobarbitúrico/análisis , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo , Ubiquinona/análogos & derivados , Ubiquinona/análisis , Vitamina E/análisis , Zinc/sangre

RESUMEN

It has been suggested that the measurement of DNA-protein cross-links (DPCs) may be of value in the assessment of an individual's exposure to specific environmental insults. For a biomarker to be reliable, its results should be consistent and specific. In the present study, the precision and specificity of the K(+)-SDS precipitation assay as a measurement for DPCs was assessed. Chinese hamster ovary (CHO) and human fibroblast cells were exposed to a number of diverse oxidative insults, whose concentrations ranged from physiological to super-physiological levels. Only super-physiological concentrations of the insults induced the formation of DPCs. Formaldehyde, chromate, vanadate, acetaldehyde, and copper were found to be the greatest inducers of DPC formation followed by manganese and iron. DPC induction was consistently higher in the CHO cells than in human fibroblast cells. While the K(+)-SDS assay may be of value as an indicator of cumulative DNA damage, its value as a biomarker for specific environmental insults may be limited.

Asunto(s)

Acetaldehído/toxicidad , Células CHO/efectos de los fármacos , Proteínas de Unión al ADN/efectos de los fármacos , Fibroblastos/efectos de los fármacos , Formaldehído/toxicidad , Metales/toxicidad , Animales , Biomarcadores , Células CHO/metabolismo , Células Cultivadas , Cromatos/toxicidad , Cobre/toxicidad , Cricetinae , Cricetulus , Daño del ADN , Proteínas de Unión al ADN/metabolismo , Relación Dosis-Respuesta a Droga , Exposición a Riesgos Ambientales , Fibroblastos/metabolismo , Humanos , Hierro/toxicidad , Intoxicación por Manganeso , Oxidación-Reducción , Estrés Oxidativo , Vanadatos/toxicidad

RESUMEN

Assessment of zinc nutriture is often compromised by the lack of reliable biomarkers. In the present study the effect of dietary zinc deprivation on plasma extracellular superoxide dismutase (EC SOD) activity was investigated in rat and rhesus macaque models. This enzyme, which contains both zinc and copper, is distinct from cytosolic copper-zinc SOD. Young, growing rats fed zinc-deficient diets (1.5 nmol Zn/g diet) were characterized by low plasma zinc concentrations and plasma EC SOD activities (16% and 56% of controls, respectively). Adolescent rhesus macaques fed diets that contained a marginal amount of zinc (30.6nmol Zn/g diet) also had low plasma zinc concentrations and low EC SOD activities compared with controls fed diets containing 765 nmol Zn/g diet (75% and 40%, respectively). Enzyme activity was not affected after in vitro addition of zinc to plasma samples from control, restrict-fed, and zinc-deficient rats. Taken together, these data support the concept that plasma EC SOD activity can be a biomarker for zinc status.

Asunto(s)

Superóxido Dismutasa/sangre , Zinc/deficiencia , Animales , Dieta , Femenino , Macaca mulatta , Masculino , Modelos Biológicos , Estado Nutricional , Ratas , Ratas Sprague-Dawley , Zinc/administración & dosificación

RESUMEN

To investigate the effects of zinc deficiency on oxidative damage to testes proteins, lipids and DNA, weanling male rats were allowed free access to low (0.5 microgram Zn/g) or adequate (25 micrograms Zn/g) zinc diets for 14 d. A third group was restricted intake of the adequate Zn diet to the amount consumed by the low Zn diet-fed group. Compared with ad libitum-fed controls, testes from rats fed the low zinc diet had lower glutamine synthetase activity, lower Fe(2+)-stimulated 2-thiobarbituric acid-reactive substances (TBARS) production, higher protein carbonyl concentrations (P < 0.05), and higher 8-oxo-2'-deoxyguanosine levels (P = 0.06). Glutamine synthetase activity in testes of the food-restricted controls was between the values for the ad libitum controls and zinc-deficient animals. Protein carbonyls were higher in the restricted controls compared with the ad libitum controls, whereas stimulated TBARS production was lower (P < 0.05). Levels of 8-oxo-2'-deoxyguanosine were lower in testes DNA of the restricted controls than in the zinc-deficient group (P < 0.05). Testes iron concentrations were higher in the zinc-deficient and restricted control rats than in ad libitum controls (P < 0.05). The oxidative damage observed may have occurred as a consequence of increased reactive oxygen species generation secondary to tissue iron accumulation and/or reductions in zinc-dependent antioxidant processes.

Asunto(s)

ADN/metabolismo , Metabolismo de los Lípidos , Proteínas/metabolismo , Testículo/metabolismo , Zinc/deficiencia , Animales , ADN/análisis , Glutamato-Amoníaco Ligasa/metabolismo , Hierro/análisis , Hierro/metabolismo , Peroxidación de Lípido , Lípidos/análisis , Masculino , Oxidación-Reducción , Proteínas/análisis , Ratas , Ratas Sprague-Dawley , Testículo/química , Testículo/enzimología , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo , Zinc/fisiología

RESUMEN

Research into the mechanisms underlying the development of age-related macular degeneration (AMD), the leading cause of visual loss in the United States and Europe in people over 60 years old, has been limited in part by the lack of animal models for this disease. In the current study, we examined 62 elderly (> or = 20 years old) rhesus macaques (Macaca mulatta) for the presence and severity of macular drusen. Drusen were observed in 47% of the macaques; they were similar histologically and in clinical appearance to the drusen observed in humans with AMD. It has been proposed that excessive tissue free radical damage may contribute to the development of AMD. Thus, circulating levels of select components of the free radical defense system and plasma thiobarbituric acid reactive substances (TBARS), an estimate of lipid peroxides, were measured in the above animals. Macaques diagnosed with drusen were characterized by alterations in concentrations and activities of several components of the free radical defense system. Alterations were most evident with respect to those enzymes associated with copper. The concept that excessive oxidative lipid damage might be a factor contributing to the occurrence of this disease is suggested by the findings of higher plasma TBARS concentrations in animals with > 10 drusen compared with animals without drusen.

Asunto(s)

Envejecimiento/fisiología , Antioxidantes/metabolismo , Degeneración Macular/veterinaria , Enfermedades de los Primates , Oligoelementos/sangre , Anciano , Animales , Ceruloplasmina/metabolismo , Cobre/sangre , Modelos Animales de Enfermedad , Femenino , Angiografía con Fluoresceína , Radicales Libres/metabolismo , Glutatión Peroxidasa/sangre , Glutatión Reductasa/sangre , Hemoglobinas/metabolismo , Humanos , Macaca mulatta , Degeneración Macular/sangre , Degeneración Macular/patología , Masculino , Persona de Mediana Edad , Epitelio Pigmentado Ocular/patología , Superóxido Dismutasa/sangre , Sustancias Reactivas al Ácido Tiobarbitúrico/análisis , Vitamina A/sangre , Vitamina E/sangre , Zinc/sangre

RESUMEN

Age-related macular degeneration (ARMD) may result from events initiated by reactive oxygen species. Blood samples from 18 patients with ARMD and 18 similarly aged controls were analysed for activities of important antioxidants. Blood glutathione reductase activity was lower in patients with ARMD compared with controls (p = 0.035). The activities of glutathione peroxidase (p = 0.18) and erythrocyte superoxide dismutase (p = 0.29) were similar between the two groups by a Student's two sample t test. Logistic regression was used to determine which enzyme activities were associated with ARMD after adjusting for possible confounding variables: smoking history, age, multivitamin use, and cardiovascular disease. Glutathione reductase activity (p = 0.05) and glutathione peroxidase activity (p = 0.065) were significantly associated with ARMD by this analysis. The relation of glutathione reductase and glutathione peroxidase activity to ARMD merits further study.

Asunto(s)

Glutatión Peroxidasa/sangre , Glutatión Reductasa/sangre , Degeneración Macular/enzimología , Anciano , Anciano de 80 o más Años , Envejecimiento/sangre , Estudios de Casos y Controles , Eritrocitos/enzimología , Femenino , Humanos , Degeneración Macular/fisiopatología , Masculino , Persona de Mediana Edad , Superóxido Dismutasa/sangre , Agudeza Visual

RESUMEN

An abnormality in the pyridoxal-5'-phosphate (PLP) dependent enzyme, glutamic acid decarboxylase (GAD), which synthesizes gamma-aminobutyric acid (GABA), may underlie the epileptic syndrome of pyridoxine-dependent seizures. GABA synthesis by skin fibroblasts from an infant with pyridoxine-dependent seizures, and from five controls, was measured. PLP independent GAD activity was similar in control and patient fibroblasts, whereas the patient's PLP dependent GAD activity was reduced compared with controls. These findings support the hypothesis for the expression of this familial disease.

Asunto(s)

Fibroblastos/metabolismo , Enfermedades Genéticas Congénitas/tratamiento farmacológico , Enfermedades Genéticas Congénitas/metabolismo , Piridoxina/uso terapéutico , Convulsiones/tratamiento farmacológico , Convulsiones/metabolismo , Ácido gamma-Aminobutírico/biosíntesis , Administración Oral , Electroencefalografía , Femenino , Fibroblastos/química , Enfermedades Genéticas Congénitas/diagnóstico , Humanos , Lactante , Infusiones Intravenosas , Convulsiones/diagnóstico , Ácido gamma-Aminobutírico/análisis

RESUMEN

Copper deficiency has been postulated result in low selenoglutathione peroxidase (Se-GSHPx) activity, secondary to alterations in the antioxidant defense system. Type I iodothyronine 5'-deiodinase contains selenium; because it is not part of the antioxidant defense system its measurement provides a way to evaluate the influence of copper on selenoenzymes independent of the antioxidant system. Weanling rats were fed the control diet (125.9 nmol Cu/g diet), copper-deficient diet (7.9 nmol Cu/g diet), or the control diet restricted to the intake of the deficient rats (restrict-fed), for 21 d. Rats fed the copper-deficient diet had cardiomegaly, low hematocrit values, and low tissue copper concentrations, but normal liver selenium concentrations. Liver and plasma Se-GSHPx activities were lowest in the deficient rats. Non-Se-GSHPx activity was similar between control and copper-deficient groups. Liver selenodeiodinase activity was lowest in the copper-deficient rats; this reduction was functionally significant as evidenced by low plasma 3,3',5-triiodothyronine and high plasma 3,3',5'-triiodothyronine concentrations.

Asunto(s)

Antioxidantes/metabolismo , Encéfalo/metabolismo , Cobre/deficiencia , Cobre/farmacología , Glutatión Peroxidasa/metabolismo , Yoduro Peroxidasa/metabolismo , Hígado/metabolismo , Animales , Encéfalo/efectos de los fármacos , Encéfalo/enzimología , Cardiomegalia , Cobre/metabolismo , Dieta , Glutatión/análogos & derivados , Glutatión/metabolismo , Disulfuro de Glutatión , Hígado/efectos de los fármacos , Hígado/enzimología , Ratas , Ratas Sprague-Dawley , Valores de Referencia , Oligoelementos/metabolismo , Destete

RESUMEN

Severe zinc deficiency in rodent models has been shown to influence the frequency of single-strand breaks in DNA isolated from liver. In the current study, we investigated whether DNA isolated from infant monkeys born to mothers fed zinc-restricted diets would be characterized by higher than normal levels of DNA damage. DNA was isolated from 30-day-old infants born to dams fed low zinc (2 or 4 micrograms Zn/g) or control zinc (50 micrograms Zn/g) diets. The amount of single-strand breaks in liver DNA was significantly higher in the low zinc group than in controls; consistent with the above, there was a trend for higher steady state levels of liver 8-hydroxy-2'-deoxyguanosine in the low zinc group. While evidence for DNA damage in the low zinc group was obtained, the activities of several antioxidant enzymes were similar between the low zinc and control groups. In summary, infants born to monkeys fed low zinc diets are characterized by evidence of DNA damage shortly after birth; this damage may be due to an increased rate of oxidative damage and/or a reduction in the rate of DNA repair.

Asunto(s)

Daño del ADN , Desoxiguanosina/análogos & derivados , Dieta , Zinc/administración & dosificación , 8-Hidroxi-2'-Desoxicoguanosina , Animales , Desoxiguanosina/metabolismo , Femenino , Hígado/química , Hígado/metabolismo , Macaca mulatta , Embarazo , Efectos Tardíos de la Exposición Prenatal , Zinc/deficiencia

RESUMEN

Low blood manganese (Mn2+) concentration is associated with epilepsy in humans and rats. The low Mn2+ concentration is attributed by some investigators to the seizure activity associated with the epilepsy, whereas others propose that the low Mn2+ concentration may be secondary to genetic mechanisms underlying the epilepsy. To begin to differentiate between these possibilities, Mn(2+)-binding enzymes of liver and brain (i.e., arginase and glutamine synthetase, respectively) were assayed in rats exposed to chronically induced seizures and in genetically epilepsy-prone rats (GEPRs). Chronic seizures caused a decrease in whole blood Mn2+ levels but did not affect brain Mn2+ concentrations. Arginase activity was increased in livers of rats with chronic seizure as compared with controls, but this difference was eliminated when Mn2+ was added to the assay. Brain glutamine synthetase activity was unaffected by chronic seizures, but the activity of this enzyme was significantly lower in GEPR brain than in control brain. Liver arginase activity tended to be lower in GEPRs, although the difference was not statistically significant. These data indicate that seizures affect liver arginase activity through changes in liver Mn2+ concentration, but GEPRs show abnormalities in Mn(2+)-dependent enzymes apparently independent of seizure activity.

Asunto(s)

Encéfalo/enzimología , Epilepsia/genética , Hígado/enzimología , Manganeso/metabolismo , Animales , Arginasa/análisis , Arginasa/metabolismo , Encéfalo/metabolismo , Epilepsia/metabolismo , Femenino , Glutamato-Amoníaco Ligasa/análisis , Glutamato-Amoníaco Ligasa/metabolismo , Hígado/metabolismo , Masculino , Manganeso/análisis , Manganeso/sangre , Modelos Neurológicos , Ratas , Ratas Sprague-Dawley , Convulsiones/genética , Convulsiones/metabolismo

RESUMEN

To investigate the effects of the severity of maternal zinc deficiency on early development, rhesus monkeys were fed diets that were either moderately zinc-deficient (MZD) (2 micrograms Zn/g) or marginal in zinc (M) (4 micrograms Zn/g) throughout pregnancy and lactation. Dams in the MZD group developed overt signs of zinc deficiency. Compared with control dams fed diets adequate in zinc (C) (50 or 100 micrograms Zn/g), both M and MZD dams showed low mitogen response. Pregnancy outcome was similar in all groups, and infants were considered healthy at delivery. From birth until d 30, infants were closely monitored for signs of zinc deficiency. On d 30, infants were killed and tissues were analyzed for several parameters reported to be affected by zinc status. MZD infants tended to have lower plasma zinc concentrations than C infants, although the difference was only significant at d 14. M infants tended to have lower plasma zinc concentrations than C infants. Mitogen response was lower in MZD and M infants than in C infants. However, mitogen responses were similar in MZD and M infants. Liver zinc concentrations were similar among the three groups of infants; however, zinc and metallothionein concentrations in (10,000 x g) liver supernatant fractions were lower in the MZD and M groups than in the C group. 65Zn absorption/retention was higher in MZD and M mothers and infants than in C mothers and infants; there were no marked differences between MZD and M mothers or infants. In contrast to whole-body absorption, 65Zn uptake/retention by isolated hepatocytes was similar among the three infant groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Asunto(s)

Intercambio Materno-Fetal , Zinc/deficiencia , Animales , Animales Recién Nacidos , Dieta , Femenino , Macaca mulatta , Metalotioneína/sangre , Estado Nutricional , Embarazo , Resultado del Embarazo , Zinc/administración & dosificación , Zinc/farmacocinética

RESUMEN

OBJECTIVE: To evaluate copper, zinc, manganese, magnesium, and other indices of peroxidative status in diabetic and nondiabetic human subjects. RESEARCH DESIGN AND METHODS: Convenience sample of 57 insulin-dependent or non-insulin-dependent diabetic subjects recruited from the diabetes clinic of the University of California, Davis, Medical Center and 28 nondiabetic subjects recruited from the staffs of the Departments of Internal Medicine and Nutrition. Individuals conducting laboratory analyses were blind to subject group. A fasting blood sample was collected from all subjects and appropriately processed for future analyses. A 24-h urine collection was obtained in a subset of subjects. RESULTS: Hyperzincuria and hypermagnesuria were evident in diabetic subjects compared with control subjects. There were no differences in plasma magnesium or whole-blood manganese between groups. Plasma copper was higher and plasma zinc was lower in diabetic than in control subjects. When data were viewed with respect to specific diabetes-associated complications, diabetic subjects with retinopathy, hypertension, or microvascular disease had higher plasma copper concentrations compared with both diabetic subjects without complications and with control subjects. There were no significant differences between control and diabetic subjects in erythrocyte copper-zinc superoxide dismutase activity or whole-blood glutathione peroxidase or glutathione reductase activities. Plasma peroxide concentrations were higher in diabetic than control subjects. CONCLUSIONS: Diabetes can alter copper, zinc, magnesium, and lipid peroxidation status. Perturbations in mineral metabolism are more pronounced in diabetic populations with specific complications. It is not known whether differences in trace element status are a consequence of diabetes, or alternatively, whether they contribute to the expression of the disease.

Asunto(s)

Cobre/sangre , Complicaciones de la Diabetes , Diabetes Mellitus/sangre , Magnesio/sangre , Manganeso/sangre , Oligoelementos/sangre , Zinc/sangre , Cobre/orina , Diabetes Mellitus/orina , Diabetes Mellitus Tipo 1/sangre , Diabetes Mellitus Tipo 1/complicaciones , Diabetes Mellitus Tipo 1/orina , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/orina , Angiopatías Diabéticas/sangre , Angiopatías Diabéticas/orina , Retinopatía Diabética/sangre , Retinopatía Diabética/orina , Eritrocitos/enzimología , Femenino , Glutatión/sangre , Humanos , Hipertensión/sangre , Hipertensión/complicaciones , Hipertensión/orina , Magnesio/orina , Masculino , Manganeso/orina , Persona de Mediana Edad , Valores de Referencia , Superóxido Dismutasa/sangre , Oligoelementos/orina , Zinc/orina

RESUMEN

In the miniature pig, ethanol consumption has been reported to induce alterations in hepatic antioxidant defense capacity, which could result in increased risk of peroxidative damage. However, ethanol may also induce changes in membrane fatty acid composition, which could reduce the risk of peroxidative damage. This study examined lipid peroxidation, antioxidant defense and fatty acid composition in livers from miniature pigs fed ethanol in diets containing 12% of their calories as fat for 20 mo. After 12 and 20 mo of feeding, ethanol-fed pigs had higher hepatic manganese-superoxide dismutase activity, lower hepatic copper concentrations and low hepatic copper-zinc-superoxide dismutase and glutathione peroxidase activities compared with controls. Lipid peroxidation as assessed by thiobarbituric acid reacting substance assay was lower in liver homogenate and mitochondrial and microsomal fractions from ethanol-fed pigs than in controls. The percentage contribution of highly unsaturated fatty acids to total fatty acids in liver homogenates (after 12 mo of feeding) and microsome fractions (after 20 mo of feeding) was lower in the ethanol-fed pigs than in the controls, resulting in a lower peroxidizability index. Ethanol-fed pigs had minimal or no hepatic damage as assessed by histological methods. We suggest that the relative resistance of microsomes to lipid peroxidation is due to the lower peroxidizability index in the ethanol-fed pigs and may account in part for the absence of significant histopathological findings after 20 mo of ethanol feeding.

Asunto(s)

Etanol/farmacología , Ácidos Grasos/metabolismo , Hígado/fisiología , Oxígeno/metabolismo , Animales , Femenino , Radicales Libres , Hígado/metabolismo , Masculino , Minerales/sangre , Minerales/metabolismo , Oxidación-Reducción , Porcinos , Porcinos Enanos , Tiobarbitúricos

RESUMEN

Cellular protection from free radical reactions was measured in hepatic tissue from controls and miniature pigs fed ethanol. The activities of copper-zinc superoxide dismutase (CuZnSOD) and glutathione peroxidase were lower and the activity of manganese superoxide dismutase (MnSOD) was higher in the pigs fed ethanol than in controls. Glutathione concentration was lower in the pigs fed ethanol than in controls. Ethanol consumption did not result in increased lipid peroxidation as assessed by thiobarbituric acid-reactive substances. The ethanol-induced effects on the activities of the superoxide dismutases may be a reflection of available metals and/or a response to increased hepatic concentration of oxygen radicals. Because the protection afforded by the glutathione system was altered, pigs fed ethanol may be at risk of peroxidative damage with continued ethanol exposure.

Asunto(s)

Alcoholismo/metabolismo , Hígado/metabolismo , Animales , Cobre/metabolismo , Modelos Animales de Enfermedad , Femenino , Radicales Libres , Glutatión/metabolismo , Glutatión Peroxidasa/metabolismo , Peroxidación de Lípido , Masculino , Manganeso/metabolismo , Superóxido Dismutasa/metabolismo , Porcinos , Porcinos Enanos , Zinc/metabolismo