Polyunsaturated fatty acid supplementation in MS.

This article focuses on polyunsaturated fatty acid (PUFA) supplementation, which is a popular form of complementary and alternative therapy among people with MS. Owing to their popularity, clinicians should be knowledgeable about the PUFA supplements that are widely available, and the efficacy and safety data from clinical studies. Small-scale studies have demonstrated trends towards some beneficial effects. PUFA supplementation is generally well tolerated, although some specific supplements are best avoided and some clinical situations warrant caution. A review of the efficacy and safety data suggests that PUFA supplementation may be a promising approach. Large-scale trials are required to confirm the benefits.

Metabolic dysfunction in familial, but not sporadic, amyotrophic lateral sclerosis.

Autosomal dominant familial amyotrophic lateral sclerosis (FALS) is associated with mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1). Previous studies have implicated the involvement of metabolic dysfunction in ALS pathogenesis. To further investigate the biochemical features of FALS and sporadic ALS (SALS), we examined SOD activity and mitochondrial oxidative phosphorylation enzyme activities in motor cortex (Brodmann area 4), parietal cortex (Brodmann area 40), and cerebellum from control subjects, FALS patients with and without known SOD mutations, SALS patients, and disease controls (Pick's disease, progressive supranuclear palsy, diffuse Lewy body disease). Cytosolic SOD activity, predominantly Cu/Zn SOD, was decreased approximately 50% in all regions in FALS patients with SOD mutations but was not significantly altered in other patient groups. Marked increases in complex I and II-III activities were seen in FALS patients with SOD mutations but not in SALS patients. We also measured electron transport chain enzyme activities in a transgenic mouse model of FALS. Complex I activity was significantly increased in the forebrain of 60-day-old G93A transgenic mice overexpressing human mutant SOD1, relative to levels in transgenic wild-type animals, supporting the hypothesis that the motor neuron disorder associated with SOD1 mutations involves a defect in mitochondrial energy metabolism.

Oxidative damage and metabolic dysfunction in Huntington's disease: selective vulnerability of the basal ganglia.

The etiology of the selective neuronal death that occurs in Huntington's disease (HD) is unknown. Several lines of evidence implicate the involvement of energetic defects and oxidative damage in the disease process, including a recent study that demonstrated an interaction between huntingtin protein and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Using spectrophotometric assays in postmortem brain tissue, we found evidence of impaired oxidative phosphorylation enzyme activities restricted to the basal ganglia in HD brain, while enzyme activities were unaltered in three regions relatively spared by HD pathology (frontal cortex, parietal cortex, and cerebellum). Citrate synthase-corrected complex II-III activity was markedly reduced in both HD caudate (-29%) and putamen (-67%), and complex IV activity was reduced in HD putamen (-62%). Complex I and GAPDH activities were unaltered in all regions examined. We also measured levels of the oxidative damage product 8-hydroxydeoxyguanosine (OH8dG) in nuclear DNA, and superoxide dismutase (SOD) activity. OH8dG levels were significantly increased in HD caudate. Cytosolic SOD activity was slightly reduced in HD parietal cortex and cerebellum, whereas particulate SOD activity was unaltered in these regions. These results further support a role for metabolic dysfunction and oxidative damage in the pathogenesis of HD.

Evidence of increased oxidative damage in both sporadic and familial amyotrophic lateral sclerosis.

Some cases of autosomal dominant familial amyotrophic lateral sclerosis (FALS) are associated with mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1), suggesting that oxidative damage may play a role in ALS pathogenesis. To further investigate the biochemical features of FALS and sporadic ALS (SALS), we examined markers of oxidative damage to protein, lipids, and DNA in motor cortex (Brodmann area 4), parietal cortex (Brodmann area 40), and cerebellum from control subjects, FALS patients with and without known SOD mutations, SALS patients, and disease controls (Pick's disease, progressive supranuclear palsy, diffuse Lewy body disease). Protein carbonyl and nuclear DNA 8-hydroxy-2'-deoxyguanosine (OH8dG) levels were increased in SALS motor cortex but not in FALS patients. Malondialdehyde levels showed no significant changes. Immunohistochemical studies showed increased neuronal staining for hemeoxygenase-1, malondialdehyde-modified protein, and OH8dG in both SALS and FALS spinal cord. These studies therefore provide further evidence that oxidative damage may play a role in the pathogenesis of neuronal degeneration in both SALS and FALS.

Superoxide dismutase concentration and activity in familial amyotrophic lateral sclerosis.

Some cases of autosomal-dominant familial amyotrophic lateral sclerosis (FALS) have been associated with mutations in SOD1, the gene that encodes Cu/Zn superoxide dismutase (Cu/Zn SOD). We determined the concentrations (microgram of Cu/Zn SOD/mg of total protein), specific activities (U/microgram of total protein), and apparent turnover numbers (U/mumol of Cu/Zn SOD) of Cu/Zn SOD in erythrocyte lysates from patients with known SOD1 mutations. We also measured the concentrations and activities of Cu/Zn SOD in FALS patients with no identifiable SOD1 mutations, sporadic ALS (SALS) patients, and patients with other neurologic disorders. The concentration and specific activity of Cu/Zn SOD were decreased in all patients with SOD1 mutations, with mean reductions of 51 and 46%, respectively, relative to controls. In contrast, the apparent turnover number of the enzyme was not altered in these patients. For the six mutations studied, there was no correlation between enzyme concentration or specific activity and disease severity, expressed as either duration of disease or age of onset. No significant alterations in the concentration, specific activity, or apparent turnover number of Cu/Zn SOD were detected in the FALS patients with no identifiable SOD1 mutations, SALS patients, or patients with other neurologic disorders. That Cu/Zn SOD concentration and specific activity are equivalently reduced in erythrocytes from patients with SOD1 mutations suggests that mutant Cu/Zn SOD is unstable in these cells. That concentration and specific activity do not correlate with disease severity suggests that an altered, novel function of the enzyme, rather than reduction of its dismutase activity, may be responsible for the pathogenesis of FALS.

Bioenergetic and oxidative stress in neurodegenerative diseases.

Aging is a major risk factor for several common neurodegenerative diseases, including Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and Huntington's disease (HD). Recent studies have implicated mitochondrial dysfunction and oxidative stress in the aging process and also in the pathogenesis of neurodegenerative diseases. In brain and other tissues, aging is associated with progressive impairment of mitochondrial function and increased oxidative damage. In PD, several studies have demonstrated decreased complex I activity, increased oxidative damage, and altered activities of antioxidant defense systems. Some cases of familial ALS are associated with mutations in the gene for Cu, Zn superoxide dismutase (Cu, Zn SOD) and decreased Cu, Zn SOD activity, while in sporadic ALS oxidative damage may be increased. Defects in energy metabolism and increased cortical lactate levels have been detected in HD patients. Studies of AD patients have identified decreased complex IV activity, and some patients with AD and PD have mitochondrial DNA mutations. The age-related onset and progressive course of these neurodegenerative diseases may be due to a cycling process between impaired energy metabolism and oxidative stress.

Cortical cytochrome oxidase activity is reduced in Alzheimer's disease.

A defect in energy metabolism may play a role in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease. In the present study, we examined the activities of the enzymes that catalyze oxidative phosphorylation in frontal, temporal, parietal, and occipital cortex from Alzheimer's disease patients and age-matched controls. Complex I and complex II-III activities showed a small decrease in occipital cortex, but were unaffected in the other cortical areas. The most consistent change was a significant decrease of cytochrome oxidase (complex IV) activity of 25-30% in the four cortical regions examined. These results provide further evidence of a cytochrome oxidase defect in Alzheimer's disease postmortem brain tissue. A deficiency in this key energy-metabolizing enzyme could lead to a reduction in energy stores and thereby contribute to the neurodegenerative process.

A frequent ala 4 to val superoxide dismutase-1 mutation is associated with a rapidly progressive familial amyotrophic lateral sclerosis.

Familial amyotrophic lateral sclerosis (FALS), a degenerative disorder of motor neurons, is associated with mutations in the Cu/Zn superoxide dismutase gene SOD1 in some affected families. We confirm a recently reported ala4-->val mutation in exon 1 of the SOD1 gene and report that this mutation is both the most commonly detected of all SOD1 mutations and among the most clinically severe. By comparison with our other FALS families, the exon 1 mutation is associated with reduced survival time after onset: 1.2 years, as compared to 2.5 years for all other FALS patients. We also demonstrate that SOD1 is prominently expressed in normal motor neurons and that neural expression of SOD1 is not prevented by this exon 1 mutation. Assays of SOD1 enzymatic activity in extracts from red blood cells, lymphoblastoid cells, and brain tissues revealed an approximately 50% reduction in activity of cytosolic SOD1 in patients with this mutation compared to normal individuals. By contrast, patients with sporadic ALS had normal levels of SOD1 enzymatic activity. Why this SOD1 mutation causes motor neuron death in FALS remains to be established. While it may be that FALS is a consequence of loss of SOD1 function, it is also possible that motor neuron death in this dominantly inherited disease occurs because the mutations confer an additional, cytotoxic function on the SOD1 protein.

Superoxide dismutase activity, oxidative damage, and mitochondrial energy metabolism in familial and sporadic amyotrophic lateral sclerosis.

The cause of neuronal death in amyotrophic lateral sclerosis (ALS) is unknown. Recently, it was found that some patients with autosomal-dominant familial ALS (FALS) have point mutations in the gene that encodes Cu/Zn superoxide dismutase (SOD1). In this study of postmortem brain tissue, we examined SOD activity and quantified protein carbonyl groups, a marker of oxidative damage, in samples of frontal cortex (Brodmann area 6) from 10 control patients, three FALS patients with known SOD1 mutations (FALS-1), one autosomal-dominant FALS patient with no identifiable SOD1 mutations (FALS-O), and 11 sporadic ALS (SALS) patients. Also, we determined the activities of components of the electron transport chain (complexes I, II-III, and IV) in these samples. The cytosolic SOD activity, which is primarily SOD1 activity, was reduced by 38.8% (p < 0.05) in the FALS-1 patients and not significantly altered in the SALS patients or the FALS-O patient relative to the control patients. The mitochondrial SOD activity, which is primarily SOD2 activity, was not significantly altered in the FALS-1, FALS-O, or SALS patients. The protein carbonyl content was elevated by 84.8% (p < 0.01) in the SALS patients relative to the control patients. Finally, the complex I activity was increased by 55.3% (p < 0.001) in the FALS-1 patients relative to the control patients. These results from cortical tissue demonstrate that SOD1 activity is reduced and complex I activity is increased in FALS-1 patients and that oxidative damage to proteins is increased in SALS patients.

Age-dependent impairment of mitochondrial function in primate brain.

It has been hypothesized that some of the functional impairments associated with aging are the result of increasing oxidative damage to mitochondrial DNA that produces defects in oxidative phosphorylation. To test this hypothesis, we examined the enzymes that catalyze oxidative phosphorylation in crude mitochondrial preparations from frontoparietal cortex of 20 rhesus monkeys (5-34 years old). Samples were assayed for complex I, complex II-III, complex IV, complex V, and citrate synthase activities. When enzyme activities were corrected for citrate synthase activities (to account for variable degrees of mitochondrial enrichment), linear regression analysis demonstrated a significant negative correlation of the activities of complex I (p < 0.002) and complex IV (p < 0.03) with age but no significant change in complex II-III or complex V activities. Relative to animals 6.9 +/- 0.9 years old (n = 7), the citrate synthase-corrected activity of complex I was reduced by 17% in animals 22.5 +/- 0.9 years old (n = 6) (p < 0.05) and by 22% in animals 30.7 +/- 0.9 years old (n = 7) (p < 0.01). Similar age-related reductions in the activities of complexes I and IV were obtained when enzyme activities were corrected for complex II-III activity. These findings show an age-associated progressive impairment of mitochondrial complex I and complex IV activities in cerebral cortices of primates.

Photoaffinity labeling of a novel benzodiazepine binding protein in rat brain.

Photoaffinity labeling experiments were conducted with [3H]clonazepam to investigate the possible existence of a benzodiazepine binding site that is distinct from the central- and peripheral-type benzodiazepine binding sites. These studies demonstrate the presence of a novel benzodiazepine binding protein in rat brain with a relative mobility of 65,000 daltons that binds benzodiazepines stereoselectivity in the high nanomolar-low micromolar concentration range.

A molecular approach to the development of anticonvulsants.

Anticonvulsants are neuronal stabilizing compounds that exhibit multiple clinical effects, including anticonvulsant, anxiolytic, sedative, and muscle-relaxant properties. This complex therapeutic picture complicates the treatment of seizure disorders in individuals with mental and developmental disorders, and frequently impairs the routine integration into society for these individuals. In order to improve the therapeutic effectiveness of these compounds, it is necessary to identify their precise molecular actions on the neuronal membrane and their effects on neuronal function. We have identified two major classes of low-affinity BZ binding sites that seem to function as generalized anticonvulsant receptors and that may mediate the anticonvulsant and sedative effects produced by these compounds. The identification of these binding sites and their anticonvulsant binding profile may clarify the complex picture of anticonvulsant mechanisms and elucidate the site(s) at which anticonvulsants produce their inhibition of MES-induced seizures and sedative effects. We will continue to examine the physiological changes induced by anticonvulsant binding at these BZ binding sites that may be a foundation for understanding the molecular basis of sedation and MES-induced seizure inhibition. Specifically, we will investigate the specific membrane components associated with the inhibition of Ca2+ channels, Na+ channel rectification, and CaM kinase II. If these goals can be achieved, then model systems could be developed to screen potential anticonvulsant or sedative compounds in the search for more effective therapeutic drugs.

Relationship between rate of digestion of foods and post-prandial glycaemia.

The amount of carbohydrate released at 1 and 5 h by digestion in vitro of 2 g carbohydrate portions of 14 foods by human digestive juices was compared with the area under the 2-h blood glucose response curve when 50 g carbohydrate portions were fed to groups of five to ten healthy volunteers. A significant relationship was found between the amounts of sugars and oligosaccharides liberated at 1 and 5 h and the food blood glucose area expressed as a percentage of the blood glucose area for 50 g glucose (r = 0.8627 and 0.8618, p less than 0.001). A significant relationship was also found between the glycaemic index and the food fibre content (p less than 0.02) and between the glycaemic index and the glucose trapping capacity of the foods (p less than 0.05). Legumes as a group liberated 56% less sugars and oligosaccharides (p less than 0.01) than the eight cereal foods over 5 h. It is suggested that such studies in vitro may help to identify food of use for diabetic patients, and at the same time throw further light on factors which affect post-prandial glycaemia.

Micromolar affinity benzodiazepine receptors: identification and characterization in central nervous system.

Receptors that selectively bind micromolar concentrations of benzodiazepines are present in rat brain membrane. These micromolar receptors exhibit saturable, stereospecific binding, and the potency of benzodiazepine binding to these receptors is correlated with the ability of the benzodiazepines to inhibit maximum electric shock-induced convulsions. Benzodiazepine receptors with nanomolar affinity differ from the micromolar receptors in their binding, kinetic, and pharmacologic characteristics. The micromolar receptors also bind phenytoin, a non-benzodiazepine anticonvulsant. These results provide evidence for a distinct class of clinically relevant benzodiazepine receptors that may regulate neuronal excitability and anticonvulsant activity.

Glycemic index of foods: a physiological basis for carbohydrate exchange.

The determine the effect of different foods on the blood glucose, 62 commonly eaten foods and sugars were fed individually to groups of 5 to 10 healthy fasting volunteers. Blood glucose levels were measured over 2 h, and expressed as a percentage of the area under the glucose response curve when the same amount of carbohydrate was taken as glucose. The largest rises were seen with vegetables (70 +/- 5%), followed by breakfast cereals (65 +/- 5%), cereals and biscuits (60 +/- 3%), fruit (50 +/- 5%), dairy products (35 +/- 1%), and dried legumes (31 +/- 3%). A significant negative relationship was seen between fat (p less than 0.01) and protein (p less than 0.001) and postprandial glucose rise but not with fiber or sugar content.