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Results for “Metabolic dysfunction”

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At least 1,243 records · Page 69Linked to original sources

PubMed1999

Relation of interictal spike frequency to 1H-MRSI-measured NAA/Cr.

PURPOSE: Whereas EEG spiking and decreases of the neuronal marker N-acetyl-aspartate (NAA) both localize well the epileptic focus, the significance of the intensity of these variables is unclear. Therefore we investigated whether the frequency of interictal surface spikes is related to the degree of N-acetyl-aspartate/creatine (NAA/Cr) ratio decrease as measured by proton magnetic resonance (MR) spectroscopic imaging (1H-MRSI) in patients with intractable partial epilepsy. METHODS: We retrospectively studied 14 patients, nine with temporal lobe epilepsy and five with frontal lobe epilepsy. Spikes that occurred during prolonged video-EEG monitoring from electrodes placed according to the International 10-20 system were counted blinded to the 1H-MRSI results. Eight electrode positions (F3/4, C3/4, T3/4, T5/6) were assigned to underlying brain subregions in the 1H-MRSI volume of interest. We converted NAA/Cr ratios into z-scores (NAA/Cr(z)) to compared NAA/Cr values directly across subregions. We calculated Spearman rank-order (p) and Pearson product-moment (r) correlations between spike frequency and NAA/Cr(z) values overall, as well as within each brain subregion. RESULTS: We found an overall negative relation between spike-frequency data and NAA/Cr(z) data (p = -0.341). When analyzing only spiking subregions, this negative relation became slightly stronger (p = -0.442; r = -0.338). When data from the eight sites were considered separately, this negative relation remained in most instances. CONCLUSIONS: Our results reveal a trend toward higher interictal spike frequencies on surface EEG in regions of pronounced neuronal metabolic damage or dysfunction. This suggests that both variables parallel an underlying pathologic substrate, although the pathophysiologic processes may be distinct.

Adolescent↗

PubMed2007

Is there a connection between severe cerebral palsy and increased gluten sensitivity?

UNLABELLED: In nine children with severe cerebral palsy (CP), feeding difficulties and poor development of weight and height, laboratory markers for metabolic and enteral dysfunction were studied. CONCLUSION: Four of the nine patients with CP had increased levels of antigliadin antibodies AGA (IgA), a finding which calls for further studies concerning the possible connection between increased celiac markers and CP.

Adolescent↗

PubMed1996

Beta-amyloidosis in normal aging and transmitter signaling in human temporal lobe.

Interactions between abnormal amyloid precursor protein metabolism and cholinergic dysfunction are increasingly apparent. Both of these major features of Alzheimer's disease occur in restricted loci in normal aging--a potential model for early Alzheimer type pathology. Entorhinal cortex is particularly vulnerable to beta-amyloidosis and compared with other cortical areas is remarkable for the relatively high density of nicotinic (3H-nicotine) but not other cholinergic or glutamate receptor binding. With increasing age, post-maturity, there is a persistent decline in nicotinic receptor binding in entorhinal cortex whereas muscarinic M1 and non-M1, glutamate NMDA and non-NMDA receptors are spared. Normal elderly individuals, distinguished by the absence of beta A4 immunoreactive plaques in this area, are differentiated from those with plaques by higher nicotine binding. Amongst individuals with an established history of smoking tobacco, nicotinic receptor binding and hippocampal choline acetyltransferase were elevated compared with non-smokers and preliminary evidence indicates a reduced density of cortical plaques. These findings are consistent with the hypothesis that down regulation of the nicotinic cholinergic receptor--a ligand gated calcium channel known to control the expression of neurotrophins--plays a role in the evolution of Alzheimer-type pathology.

Adolescent↗

PubMed2002

Iron transport: emerging roles in health and disease.

In the theater of cellular life, iron plays an ambiguous and yet undoubted lead role. Iron is a ubiquitous core element of the earth and plays a central role in countless biochemical pathways. It is integral to the catalysis of the redox reactions of oxidative phosphorylation in the respiratory chain, and it provides a specific binding site for oxygen in the heme binding moiety of hemoglobin, which allows oxygen transport in the blood. Its biological utility depends upon its ability to readily accept or donate electrons, interconverting between its ferric (Fe3+) and ferrous (Fe2+) forms. In contrast to these beneficial features, free iron can assume a dangerous aspect catalyzing the formation of highly reactive compounds such as cytotoxic hydroxyl radicals that cause damage to the macromolecular components of cells, including DNA and proteins, and thereby cellular destruction. The handling of iron in the body must therefore be very carefully regulated. Most environmental iron is in the Fe3+ state, which is almost insoluble at neutral pH. To overcome the virtual insolubility and potential toxicity of iron, a myriad of specialized transport systems and associated proteins have evolved to mediate regulated acquisition, transport, and storage of iron in a soluble, biologically useful, non-toxic form. We are gradually beginning to understand how these proteins individually and in concert serve to maintain cellular and whole body homeostasis of this crucial yet potentially harmful metal ion. Furthermore, studies are increasingly implicating iron and its associated transport in specific pathologies of many organs. Investigation of the transport proteins and their functions is beginning to unravel the detailed mechanisms underlying the diseases associated with iron deficiency, iron overload, and other dysfunctions of iron metabolism.

Biological Transport↗

PubMed1995

Ethanol neurobehavioural teratogenesis and the role of L-glutamate in the fetal hippocampus.

The purpose of this article is to review the current state of knowledge of ethanol neurobehavioural teratogenesis and its postulated mechanisms. The review comprises an examination of ethanol teratogenesis in the human, including the fetal alcohol syndrome, and in experimental animals. Several current proposed mechanisms of ethanol neurobehavioural teratogenesis are critically assessed, including the role of acetaldehyde as the proximate metabolite of ethanol; fetal hypoxia; placental dysfunction; fetal prostaglandin metabolism; and action of ethanol on developing neurons in the fetal brain, including the hippocampus, one of ethanol's main target sites. The effect of ethanol on the release of L-glutamate, an excitatory amino acid neurotransmitter, in the fetal hippocampus is described, and the role of L-glutamate in ethanol teratogenesis involving the hippocampus is discussed. A novel mechanism for abnormal neuronal development in the fetal hippocampus produced by prenatal ethanol exposure is presented, and future experiments to test this hypothesis are proposed.

Animals↗

PubMed2003

Profiling substrate fluxes in the isolated working mouse heart using 13C-labeled substrates: focusing on the origin and fate of pyruvate and citrate carbons.

The availability of genetically modified mice requires the development of methods to assess heart function and metabolism in the intact beating organ. With the use of radioactive substrates and ex vivo perfusion of the mouse heart in the working mode, previous studies have documented glucose and fatty acid oxidation pathways. This study was aimed at characterizing the metabolism of other potentially important exogenous carbohydrate sources, namely, lactate and pyruvate. This was achieved by using (13)C-labeling methods. The mouse heart perfusion setup and buffer composition were optimized to reproduce conditions close to the in vivo milieu in terms of workload, cardiac functions, and substrate-hormone supply to the heart (11 mM glucose, 0.8 nM insulin, 50 microM carnitine, 1.5 mM lactate, 0.2 mM pyruvate, 5 nM epinephrine, 0.7 mM oleate, and 3% albumin). The use of three differentially (13)C-labeled carbohydrates and a (13)C-labeled long-chain fatty acid allowed the quantitative assessment of the metabolic origin and fate of tissue pyruvate as well as the relative contribution of substrates feeding acetyl-CoA (pyruvate and fatty acids) and oxaloacetate (pyruvate) for mitochondrial citrate synthesis. Beyond concurring with the notion that the mouse heart preferentially uses fatty acids for energy production (63.5 +/- 3.9%) and regulates its fuel selection according to the Randle cycle, our study reports for the first time in the mouse heart the following findings. First, exogenous lactate is the major carbohydrate contributing to pyruvate formation (42.0 +/- 2.3%). Second, lactate and pyruvate are constantly being taken up and released by the heart, supporting the concept of compartmentation of lactate and glucose metabolism. Finally, mitochondrial anaplerotic pyruvate carboxylation and citrate efflux represent 4.9 +/- 1.8 and 0.8 +/- 0.1%, respectively, of the citric acid cycle flux and are modulated by substrate supply. The described (13)C-labeling strategy combined with an experimental setup that enables continuous monitoring of physiological parameters offers a unique model to clarify the link between metabolic alterations, cardiac dysfunction, and disease development.

Acetyl Coenzyme A↗

PubMed2004

Chronic maternal feed restriction impairs growth but increases adiposity of the fetal guinea pig.

Small size at birth has been associated with an increased risk of central obesity and reduced lean body mass in adult life. This study investigated the time of onset of prenatally induced obesity, which occurs after maternal feed restriction, in the guinea pig, a species that, like the human, develops substantial adipose tissue stores before birth. We examined the effect of maternal feed restriction [70% ad libitum intake from 4 wk before to midpregnancy, then 90% until day 60 gestation (term approximately 69 days)] on fetal growth and body composition in the guinea pig. Maternal feed restriction reduced fetal (-39%) and placental (-30%) weight at 60 days gestation and reduced liver, biceps muscle, spleen, and thymus weights, relative to fetal weight, while relative weights of brain, lungs, and interscapular and retroperitoneal fat pads were increased. In the interscapular depot, maternal feed restriction decreased the volume density of multilocular fat and increased that of unilocular fat, resulting in an increased relative weight of interscapular unilocular fat. Maternal feed restriction did not alter the relative weight of perirenal fat or the volume density of adipocyte populations within the depot but increased unilocular lipid locule size. Maternal feed restriction in the guinea pig is associated with decreased weight of major organs, including liver and skeletal muscle, but increased adiposity of the fetus, with relative sparing of unilocular adipose tissue. If this early-onset obesity persists, it may contribute to the metabolic and cardiovascular dysfunction that these offspring of feed-restricted mothers develop as adults.

Adipose Tissue↗

PubMed1987

Hyperoxia damages phagocytic defenses of neonatal rabbit lung.

The effect of hyperoxia on phagocytic defenses of neonatal rabbit lung was ascertained by exposure to a fractional inspired O2 concentration of 0.95 + or 0.21 for 48, 96, or 168 h. Intrapulmonary clearance of inhaled staphylococci was reduced by 67 and 74% after 96 and 168 h in hyperoxia (P less than 0.05). Impaired phagocytic killing was not due to diminished bacterial ingestion. Alveolar macrophages (AM) lavaged from pups reared in normoxia had a progressive ability to release superoxide (O-2) and showed increasing cyanide-sensitive O2 consumption during the 1st wk of life. Conversely, AM recovered from litters housed in hyperoxia for 48 h produced 190% more O-2 than normoxic controls (P less than 0.005), but this capacity to generate O-2 fell by 43% after 96 h of exposure (P less than 0.05). After 96 h of hyperoxia, AM had a significant shift toward cyanide-insensitive metabolism compared with normoxic cells (P less than 0.05). Polymorphonuclear leukocytes (PMN) entered the alveoli after 96 h of hyperoxia, and mortality rose abruptly in animals exposed for 168 h (16%) vs. 96 h (3%). Our findings indicate neonatal hyperoxia induces metabolic and bactericidal dysfunction in the primary pulmonary phagocyte, the AM, and this injury is followed by additional lung insult during PMN migration into the airways.

Animals↗

PubMed1999

Alterations of heart function and Na+-K+-ATPase activity by etomoxir in diabetic rats.

To examine the role of changes in myocardial metabolism in cardiac dysfunction in diabetes mellitus, rats were injected with streptozotocin (65 mg/kg body wt) to induce diabetes and were treated 2 wk later with the carnitine palmitoyltransferase inhibitor (carnitine palmitoyltransferase I) etomoxir (8 mg/kg body wt) for 4 wk. Untreated diabetic rats exhibited a reduction in heart rate, left ventricular systolic pressure, and positive and negative rate of pressure development and an increase in end-diastolic pressure. The sarcolemmal Na+-K+-ATPase activity was depressed and was associated with a decrease in maximal density of binding sites (Bmax) value for high-affinity sites for [3H]ouabain, whereas Bmax for low-affinity sites was unaffected. Treatment of diabetic animals with etomoxir partially reversed the depressed cardiac function with the exception of heart rate. The high serum triglyceride and free fatty acid levels were reduced, whereas the levels of glucose, insulin, and 3,3',-5-triiodo-L-thyronine were not affected by etomoxir in diabetic animals. The activity of Na+-K+-ATPase expressed per gram heart weight, but not per milligram sarcolemmal protein, was increased by etomoxir in diabetic animals. Furthermore, Bmax (per g heart wt) for both low-affinity and high-affinity binding sites in control and diabetic animals was increased by etomoxir treatment. Etomoxir treatment also increased the depressed left ventricular weight of diabetic rats and appeared to increase the density of the sarcolemma and transverse tubular system to normalize Na+-K+-ATPase activity. Therefore, a shift in myocardial substrate utilization may represent an important signal for improving the depressed cardiac function and Na+-K+-ATPase activity in diabetic rat hearts with impaired glucose utilization.

Animals↗

PubMed1998

Surgical challenge of massive bilateral staghorn renal calculi in a spinal cord injury patient.

We report a rare case of massive bilateral staghorn calculi in a spinal cord injury patient with significant renal compromise. The patient was successfully treated with percutaneous nephrolithotomy to achieve a stone-free status. The various options of treatment are discussed with special attention to the technical aspects necessary to achieve complete eradication of the stone burden during percutaneous nephrolithotomy. Furthermore, the importance of treating bladder dysfunction and urinary metabolic abnormalities is emphasized.

Follow-Up Studies↗

PubMed1997

The molecular basis of disorders caused by defects in G proteins.

G proteins couple receptors for many hormones to effectors that regulate second messenger metabolism. G protein dysfunction could involve gain or loss of function. For Gs, the G protein that couples receptors to stimulation of cAMP formation, examples of both types have already been defined. Germline loss of function mutations in the Gs(alpha) gene are responsible for a form of inherited hormone resistance termed pseudohypoparathyroidism (Albright hereditary osteodystrophy). Conversely, somatic gain of function mutations cause constitutive stimulation of cAMP, independent of receptor activation, in acromegaly, in hyperfunctional thyroid nodules, and in the McCune-Albright syndrome. Future work is likely to uncover additional disorders caused by defective G proteins with implications for diagnosis and treatment.

Acromegaly↗

PubMed2001

Use of human immunodeficiency virus-1 protease inhibitors is associated with atherogenic lipoprotein changes and endothelial dysfunction.

BACKGROUND: Human immunodeficiency virus protease inhibitors (HIV PIs) are associated with hyperlipidemia, hyperglycemia, and obesity; however, it is not known whether they increase risk of atherosclerotic vascular disease. The purposes of this study were to characterize the lipoprotein abnormalities associated with use of HIV PIs in individuals with HIV infection and to determine the pathophysiological significance of these changes by assessing their effect on endothelial dysfunction. METHODS AND RESULTS: This was a cross-sectional study of 37 adults with HIV-1 infection who were receiving antiretroviral therapy. Twenty-two were taking HIV PIs (group 1); 15 were not (group 2). Lipids and lipoproteins were measured by enzymatic techniques and nuclear magnetic resonance spectroscopic analysis. Flow-mediated vasodilation (FMD) of the brachial artery was measured by high-resolution ultrasound. Subjects in both groups were similar in regard to age, time since diagnosis of HIV infection, and CD4 cell count. Group 1 subjects had higher total cholesterol (5.68 versus 4.42 mmol/L, P=0.007) and triglyceride (4.43 versus 1.98 mmol/L, P=0.009) levels, characterized by elevated levels of IDL and VLDL. Subjects in group 1 had impaired FMD (2.6+/-4.6%), indicative of significant endothelial dysfunction. Group 2 subjects had normal FMD (8.1+/-6.7%, P=0.005). In group 1, chylomicron, VLDL, IDL, and HDL cholesterol levels predicted FMD. CONCLUSIONS: Use of HIV PIs is associated with atherogenic lipoprotein changes and endothelial dysfunction. Because these metabolic and vascular changes predispose to atherosclerosis, monitoring and treatment of dyslipidemia in patients taking these medications is warranted.

Adult↗

PubMed2000

Leptin attenuates cardiac contraction in rat ventricular myocytes. Role of NO.

Obesity is commonly associated with impaired myocardial contractile function. However, a direct link between these 2 states has not yet been established. There has been an indication that leptin, the product of the human obesity gene, may play a role in obesity-related metabolic and cardiovascular dysfunctions. The purpose of this study was to determine whether leptin exerts any direct cardiac contractile action that may contribute to altered myocardial function. Ventricular myocytes were isolated from adult male Sprague-Dawley rats. Contractile responses were evaluated by use of video-based edge detection. Contractile properties analyzed in cells electrically stimulated at 0.5 Hz included peak shortening, time to 90% peak shortening, time to 90% relengthening, and fluorescence intensity change. Leptin exhibited a dose-dependent inhibition in myocyte shortening and intracellular Ca(2+) change, with maximal inhibitions of 22.4% and 26.2%, respectively. Pretreatment with the NO synthase inhibitor N:(omega)-nitro-L-arginine methyl ester (L-NAME, 100 micromol/L) blocked leptin-induced inhibition of both peak shortening and fluorescence intensity change. Leptin also stimulated NO synthase activity in a time- and concentration-dependent manner, as reflected in the dose-related increase in NO accumulation in these cells. Addition of an NO donor (S-nitroso-N-acetyl-penicillamine [SNAP]) to the medium mimicked the effects of leptin administration. In summary, this study demonstrated a direct action of leptin on cardiomyocyte contraction, possibly through an increased NO production. These data suggest that leptin may play a role in obesity-related cardiac contractile dysfunction.

Animals↗

PubMed1998

Hydrogen peroxide activates mitogen-activated protein kinases and Na+-H+ exchange in neonatal rat cardiac myocytes.

Reperfusion of cardiac tissue after an ischemic episode is associated with metabolic and contractile dysfunction, including reduced tension development and activation of the Na+-H+ exchanger (NHE). Oxygen-derived free radicals are key mediators of reperfusion abnormalities, although the cellular mechanisms involved have not been fully defined. In the present study, the effects of free radicals on mitogen-activated protein (MAP) kinase function were investigated using cultured neonatal rat ventricular myocytes. Acute exposure of spontaneously beating myocytes to 50 micromol/L hydrogen peroxide (H2O2) caused a sustained decrease in contraction amplitude (80% of control). MAP kinase activity was measured by in-gel kinase assays and Western blot analysis. Acute exposure to H2O2 (100 micromol/L, 5 minutes) resulted in sustained MAP kinase activation that persisted for 60 minutes. Catalase, but not superoxide dismutase, completely inhibited MAP kinase activation by H2O2. Pretreatment with chelerythrine (10 micromol/L, 45 minutes), a protein kinase C inhibitor, or genistein (75 micromol/L, 45 minutes) or herbimycin A (3 micromol/L, 45 minutes), tyrosine kinase inhibitors, caused significant inhibition of H2O2-stimulated MAP kinase activity (51%, 78%, and 45%, respectively, at 20 minutes). Brief exposure to H2O2 also stimulated NHE activity. This effect was completely abolished by pretreatment with the MAP kinase kinase inhibitor PD 98059 (30 micromol/L, 60 minutes). These results suggest that low doses of H2O2 induce MAP kinase-dependent pathways that regulate NHE activity during reperfusion injury.

Animals↗

PubMed1997

Association analysis of the catechol O-methyltransferase gene and bipolar affective disorder.

OBJECTIVE: Catechol O-methyltransferase (COMT) is an enzyme that inactivates catecholamines. Two common COMT alleles determine high and low activity of the enzyme. Previous studies using biochemical methods found lower enzyme activity in patients with major depression and bipolar disorder in comparison with control values, suggesting that a dysfunction in catecholamine metabolism may be related to the etiology of depression. METHOD: The authors studied two recently described DNA polymorphisms at the COMT gene (a silent C256G mutation and a structural mutation, Val-108-Met) in 88 patients with bipolar disorder and in 113 healthy comparison subjects, all of Spanish origin. RESULTS: The frequency of the C256 allele was 0.58 in the patients and 0.54 in the comparison subjects. The frequency of the Val108 variant was 0.57 for both the patients and the comparison subjects. No allelic or genotypic associations were observed. CONCLUSIONS: The lack of association suggests that the COMT gene is not a major risk factor for bipolar disorder.

Alleles↗

PubMed2006

Fabry's disease: otoneurologic findings in twelve members of one family.

Fabry's disease corresponds to an inherited disorder transmitted by an X-linked recessive gene. It generates a dysfunction of glycosphingolipid metabolism due to an enzymatic deficiency of alpha-galactosidase activity, resulting in glycosphingolipid deposits in all areas of the body. The clinical (heart, kidney, and central nervous system) manifestations are more severe in hemizygous boys than in heterozygous girls. They appear during childhood or adolescence: acroparesthesia, joint pain, angiokeratoma, corneal dystrophy, hypohydrosis or anhydrosis, and renal failure. The otoneurologic symptoms consist of hearing fluctuation, progressive unilateral or bilateral hearing loss, and episodes of vertigo or dizziness. Otoneurologic findings in 12 of 26 members of the same family are presented: the mother and 9 of her 12 children, as well as 2 of her 14 grandchildren: 4 healthy persons, 4 heterozygous female carriers, and 4 hemizygous male patients. Three of the male patients had fluctuation of hearing, sudden hearing loss, and episodes of vertigo and dizziness. The otoneurologic examinations showed a bilateral cochleovestibular deficit (n = 1), a right cochleovestibular deficit (n = 1), and a bilateral hearing loss combined with a right vestibular deficit (n = 1). Histopathologic evidence of glycosphingolipid accumulation in vascular endothelial and ganglion cells, as well as atrophy of the stria and spiral ligament, might explain the otoneurologic symptoms and findings.

Adult↗

PubMedDate not supplied

Serum leptin levels in acute protein deprivation.

BACKGROUND: Protein energy malnutrition (PEM) induces a host neuroendocrine response, reflected by significant elevations in circulating glucocorticoid levels and associated with metabolic and immune dysfunction. Leptin regulates food intake and body mass and has a significant impact on the hypothalamic-pituitary-adrenal axis (HPA). We hypothesized that leptin may be altered by and may play an important role in regulating the effects of PEM. METHODS: Female Balb/c mice were used. In experiment 1, mice were pair-fed either a protein-free (0% casein) or control (24% casein) diet for 7 days. In experiment 2, mice were implanted with either a placebo or corticosterone-releasing pellet and fed the control diet for 7 days. In experiment 3, adrenalectomized mice were pair-fed either the protein-free or control diet for 7 days. Serum corticosterone and leptin levels were measured in all experiments. RESULTS: PEM caused significant reductions in food intake, body weight, and total body fat, but not lean body mass. Serum corticosterone and leptin levels were significantly greater in mice fed the protein-free diet. Subcutaneous implantation of a corticosterone pellet in mice fed the control diet resulted in a significantly elevated serum leptin level compared with placebo-implanted controls. Bilateral adrenalectomy partially blunted the increased serum leptin in PEM. CONCLUSIONS: Leptin may be an important mediator of weight loss and decreased food intake in PEM. Elevated serum leptin in PEM may be secondary to elevated serum corticosterone, with other factors inherent in the host response to protein restriction also contributing to elevated serum leptin.

Acute Disease↗

PubMed1994

New environmental agents associated with lupus-like disorders.

An increasing number of environmental agents are being investigated as possible risk factors in the etiology of certain connective tissue disorders. Exposure to a variety of therapeutic agents, foods and dietary supplements, occupational and other toxic exposures, and infectious agents has been associated with the onset of lupus-like disorders. The mechanisms by which these agents might induce lupus remain unknown but may involve alteration of cellular components or activation of the immune system. Individual host susceptibility factors, including pre-existing organ dysfunction and particular metabolic enzyme or immunogenetic phenotypes, may also be important risk factors for development of environmentally-associated lupus-like disorders. Awareness of the many environmental agents implicated with lupus and related disorders, and dissection of their pathogenetic mechanisms through appropriate case-controlled investigations, may identify additional toxic agents and may lead to a better understanding of the idiopathic lupus syndromes.

Connective Tissue Diseases↗