Decreased glucose-6-phosphate dehydrogenase activity along with oxidative stress affects visual contrast sensitivity in alcoholics.

OBJECTIVE: To evaluate oxidative stress and glucose-6-phosphate dehydrogenase (G6PD) status of alcoholics and discern their association, if any, with visual contrast sensitivity function. METHODS: Forty male alcoholic subjects and 36 male non-alcoholic subjects with the same age and nutritional status were enrolled in this study. Serum malondialdehyde (MDA) level and glucose-6-phosphate dehydrogenase (G6PD) activity of erythrocytes were determined by spectrophotometric assay. Contrast sensitivity (CS) function of study subjects was measured using the Rabin Contrast Sensitivity Test (Precision Vision®, La Salle, Illinois, United States). RESULTS: Serum MDA levels were significantly higher (p < 0.0001) and erythrocyte G6PD activity was significantly lower (p = 0.0026) in alcoholic subjects compared to the controls. CS scores of both eyes were also found to be decreased significantly in alcoholic subjects (both at p < 0.0001) compared to control subjects. On the other hand, CS scores of the alcoholic subjects were inversely correlated with the serum MDA level (r = -0.746, p < 0.0001) and directly correlated with erythrocyte G6PD activity (r = 0.78, p < 0.0001). A strong inverse correlation (r = -0.84, p < 0.0001) was also observed between serum MDA level and erythrocyte G6PD activity of alcoholic subjects. CONCLUSION: Reduced G6PD activity and increased serum MDA level might be the key cause of the early visual abnormalities, such as reduced CS function of the alcoholic subjects.

Role of Pro-Inflammatory Cytokines and Vitamin D in Probable Alzheimer's Disease with Depression.

Symptoms of depression are present in a significant proportion of Alzheimer's disease (AD) patients. While epidemiological studies have shown a strong association between depression and AD, it has not been established whether depression is a risk factor or merely a co-morbidity of AD. It is also uncertain if depression affects the pathogenesis of AD. In this paper, we address these questions by measuring the serum levels of two common metabolic risk factors of AD and depression, inflammatory cytokines (IL 6 and TNF alpha) and serum 25-hydroxyvitamin D, in a case-control study. We measured the serum levels of IL 6, TNF α and 25-hydroxyvitamin D in age-matched healthy controls (n= 60) and in AD patients without depression (n=26) or AD patients with depression (n=34), and statistically analyzed the changes in these parameters among different groups under this study. Our results show that in AD there is a significant increase in IL 6 and TNF α and a marked decrease in 25-hydroxyvitamin D in the peripheral circulation compared to age-matched healthy controls. Furthermore, AD patients with depression have even significantly higher levels of IL 6 or TNF α and a lower level of 25-hydroxyvitamin D in circulation than in AD patients without depression. We also found a strong statistical correlation between the disease severity and the serum levels of IL 6, TNF α and 25-hydroxyvitamin D in AD patients with depression. These results suggest that altered circulating levels of common metabolic risk factors lead to the co-existence of depression with AD in many patients, and when they co-exist, the depression presumably affects the severity of AD presentations through more aggravated changes in these risk factors.

Role of Serum Adiponectin and Vitamin D in Prediabetes and Diabetes Mellitus.

OBJECTIVES: The roles of deficient or deranged insulin, adiponectin and 25 hydroxy vitamin D (25[OH]D) levels regulating food intake, energy metabolism, glucose and lipid metabolism and body weight have been reported in the pathogenesis of prediabetes and type 2 diabetes mellitus. However, their congruity in the etiology of diabetes mellitus is unknown. Thus, the aim of the study was to investigate the roles of these parameters together and to establish their interrelationship in patients with prediabetes and diabetes. METHODS: The preliminary cross-sectional study included 77 persons with type 2 diabetes who were matched for age, sex and body mass index (BMI); 73 persons with prediabetes; and 52 healthy control subjects. Fasting serum levels of adiponectin, insulin and 25(OH)D were measured by commercially available immune assay kits, and routine biochemical parameters were analyzed in all study groups. RESULTS: The results show statistically significant lower levels of serum adiponectin and serum 25(OH)D and higher serum insulin levels in persons with prediabetes or type 2 diabetes with respect to controls. The changes in the serum adiponectin or serum 25(OH)D in persons with prediabetes and type 2 diabetes were found to be inversely correlated with the serum levels of insulin. Moreover, multiple linear regression analysis, with 25(OH)D, insulin and homeostatic model assessment-insulin resistance (HOMA-IR) as the variables, revealed that serum adiponectin levels might be an independent risk factor for the progression of prediabetes and type 2 diabetes in subjects. CONCLUSIONS: The association of these hormones might act as a significant predictor of progression of prediabetes to type 2 diabetes. Decreased serum adiponectin levels might be an independent risk factor for progression to prediabetes and type 2 diabetes, which may help in developing experimental models of the disease or in identifying biomarkers or disease-modifying drugs.

Genistein, the Isoflavone in Soybean, Causes Amyloid Beta Peptide Accumulation in Human Neuroblastoma Cell Line: Implications in Alzheimer's Disease.

The isoflavone, genistein, present in soybean is being actively investigated for its potential beneficial effect against Alzheimer's disease. Our data, however, show that in SHSY5Y cells genistein causes increased expression (mRNA and protein) of amyloid precursor protein (APP), increased mRNA expression and activity of ß-secretase and diminished level of insulin degrading enzyme (IDE) which also degrades amyloid beta peptide. These effects of genistein lead to enhanced accumulation of amyloid beta peptide (Aß42) in SHSY5Y cells. The results do not support the view that genistein could be a putative drug against AD and instead strengthen the epidemiological study which implies that genistein content of soybean food product (Tofu) leads to cognitive impairment.

Vitamin D and Alzheimer's Disease: Neurocognition to Therapeutics.

Alzheimer's disease (AD), the major cause of dementia worldwide, is characterized by progressive loss of memory and cognition. The sporadic form of AD accounts for nearly 90% of the patients developing this disease. The last century has witnessed significant research to identify various mechanisms and risk factors contributing to the complex etiopathogenesis of AD by analyzing postmortem AD brains and experimenting with animal and cell culture based models. However, the treatment strategies, as of now, are only symptomatic. Accumulating evidences suggested a significant association between vitamin D deficiency, dementia, and AD. This review encompasses the beneficial role of vitamin D in neurocognition and optimal brain health along with epidemiological evidence of the high prevalence of hypovitaminosis D among aged and AD population. Moreover, disrupted signaling, altered utilization of vitamin D, and polymorphisms of several related genes including vitamin D receptor (VDR) also predispose to AD or AD-like neurodegeneration. This review explores the relationship between this gene-environmental influence and long term vitamin D deficiency as a risk factor for development of sporadic AD along with the role and rationale of therapeutic trials with vitamin D. It is, therefore, urgently warranted to further establish the role of this potentially neuroprotective vitamin in preventing and halting progressive neurodegeneration in AD patients.

Metabolic Risk Factors of Sporadic Alzheimer's Disease: Implications in the Pathology, Pathogenesis and Treatment.

Alzheimer's disease (AD), the major cause of dementia among the elderly world-wide, manifests in familial and sporadic forms, and the latter variety accounts for the majority of the patients affected by this disease. The etiopathogenesis of sporadic AD is complex and uncertain. The autopsy studies of AD brain have provided limited understanding of the antemortem pathogenesis of the disease. Experimental AD research with transgenic animal or various cell based models has so far failed to explain the complex and varied spectrum of AD dementia. The review, therefore, emphasizes the importance of AD related risk factors, especially those with metabolic implications, identified from various epidemiological studies, in providing clues to the pathogenesis of this complex disorder. Several metabolic risk factors of AD like hypercholesterolemia, hyperhomocysteinemia and type 2 diabetes have been studied extensively both in epidemiology and experimental research, while much less is known about the role of adipokines, pro-inflammatory cytokines and vitamin D in this context. Moreover, the results from many of these studies have shown a degree of variability which has hindered our understanding of the role of AD related risk factors in the disease progression. The review also encompasses the recent recommendations regarding clinical and neuropathological diagnosis of AD and brings out the inherent uncertainty and ambiguity in this area which may have a distinct impact on the outcome of various population-based studies on AD-related risk factors.

Enhanced ROS production and oxidative damage in subcutaneous white adipose tissue mitochondria in obese and type 2 diabetes subjects.

Oxidative stress in the insulin target tissues has been implicated in the pathophysiology of type 2 diabetes. The study has examined the oxidative stress parameters in the mitochondria of subcutaneous white adipose tissue from obese and non-obese subjects with or without type 2 diabetes. An accumulation of protein carbonyls, fluorescent lipid peroxidation products, and malondialdehyde occurs in the adipose tissue mitochondria of obese type 2 diabetic, non-diabetic obese, and non-obese diabetic subjects with the maximum increase noticed in the obese type 2 diabetes patients and the minimum in non-obese type 2 diabetics. The mitochondria from obese type 2 diabetics, non-diabetic obese, and non-obese type 2 diabetics also produce significantly more reactive oxygen species (ROS) in vitro compared to those of controls, and apparently the mitochondrial ROS production rate in each group is proportional to the respective load of oxidative damage markers. Likewise, the mitochondrial antioxidant enzymes like superoxide dismutase and glutathione peroxidase show decreased activities most markedly in obese type 2 diabetes subjects and to a lesser degree in non-obese type 2 diabetes or non-diabetic obese subjects in comparison to control. The results imply that mitochondrial dysfunction with enhanced ROS production may contribute to the metabolic abnormality of adipose tissue in obesity and diabetes.

α-Synuclein-induced mitochondrial dysfunction in isolated preparation and intact cells: implications in the pathogenesis of Parkinson's disease.

This study has shown that purified recombinant human α-synuclein (20 µM) causes membrane depolarization and loss of phosphorylation capacity of isolated purified rat brain mitochondria by activating permeability transition pore complex. In intact SHSY5Y (human neuroblastoma cell line) cells, lactacystin (5 µM), a proteasomal inhibitor, causes an accumulation of α-synuclein with concomitant mitochondrial dysfunction and cell death. The effects of lactacystin on intact SHSY5Y cells are, however, prevented by knocking down α-synuclein expression by specific siRNA. Furthermore, in wild-type (non-transfected) SHSY5Y cells, the effects of lactacystin on mitochondrial function and cell viability are also prevented by cyclosporin A (1 µM) which blocks the activity of the mitochondrial permeability transition pore. Likewise, in wild-type SHSY5Y cells, typical mitochondrial poison like antimycin A (50 nM) produces loss of cell viability comparable to that of lactacystin (5 µM). These data, in combination with those from isolated brain mitochondria, strongly suggest that intracellularly accumulated α-synuclein can interact with mitochondria in intact SHSY5Y cells causing dysfunction of the organelle which drives the cell death under our experimental conditions. The results have clear implications in the pathogenesis of sporadic Parkinson's disease. α-Synuclein is shown to cause mitochondrial impairment through interaction with permeability transition pore complex in isolated preparations. Intracellular accumulation of α-synuclein in SHSY5Y cells following proteasomal inhibition leads to mitochondrial impairment and cell death which could be prevented by knocking down α-synuclein gene. The results link mitochondrial dysfunction and α-synuclein accumulation, two key pathogenic mechanisms of Parkinson's disease, in a common damage pathway.

Raised serum proinflammatory cytokines in Alzheimer's disease with depression.

The purpose of the present study was to identify the changes in the levels of proinflammatory cytokines like IL-1ß, IL-6 and TNF-α in peripheral circulation in Alzheimer's disease (AD) subjects and to correlate these with associated depression and cognitive deficit. Fifty five AD subjects and thirty seven age and sex matched controls were included in the study. The AD patients were grouped as AD with depression (n= 31) and AD without depression (n= 24). The serum levels of IL-1ß, IL-6 and TNF-α were determined by immunoassay by commercially available kits. The serum levels of IL-6 and TNF-α were elevated in AD patients with depression compared to control (p<0.001) or AD without depression (p<0.001). The serum level of IL-1ß was higher in AD patients with or without depression as compared to controls. Furthermore, a strong inverse correlation was observed between the MMSE scores and serum levels of IL-6 or TNF-α in AD subjects with depression. The study highlights the important role of peripheral IL-6 and TNF-α in AD associated depression and cognitive deficits.

Altered serum levels of adipokines and insulin in probable Alzheimer's disease.

Cerebral hypometabolism of glucose, weight loss, and decreased food intake are characteristic features of sporadic Alzheimer's disease (AD). A systematic study on the serum levels of adipokines and insulin, the major hormones regulating energy metabolism, food intake, and body weight, in sporadic AD is necessary. The present study compares the serum levels of leptin, adiponectin, and insulin, measured by commercially available immuno-assay kits, between controls and sporadic AD subjects. The results show a conspicuous decrease in the level of leptin, a dramatic rise in the level of adiponectin, and also a statistically significant increase in insulin level, in the blood of AD subjects, with respect to controls. The changes in the serum levels of adiponectin and insulin in AD are positively correlated with the severity of dementia. Likewise, the serum level of leptin in AD subjects is negatively correlated with the degree of dementia. The changes in the levels of adipokines and insulin have implications in the amyloid pathology, neurodegeneration, and hypometabolism of glucose existing in the AD brain.

Serum Homocysteine, Dehydroepiandrosterone Sulphate and Lipoprotein (a) in Alzheimer's Disease and Vascular Dementia.

Alzheimer's disease (AD) and vascular dementia (VAD) are the major forms of dementia affecting elderly people, in which the levels of many metabolites are altered in cerebrospinal fluid (CSF) and serum. These metabolites could be risk factors or potential biomarkers, but the significance of some of these are not clearly understood in the context of the disease pathogenesis. In the present study serum levels of homocysteine, dehydroepiandrosterone sulphate (DHEA-S) and lipoprotein (a) or Lp(a) have been measured by ELISA using commercial kits in AD (n = 40), VAD (n = 40) and age matched control subjects (n = 40). The data are compared by ANOVA and post-hoc analysis. The serum homocysteine is markedly elevated compared to control both in AD and VAD subjects, but to a significantly higher extent in the latter. Lp(a) is increased in the serum of VAD subjects only compared to control. Likewise, serum DHEA-S level is lowered in AD but not in VAD compared to control. The analysis of the present data and those published by others suggest that alterations in homocysteine and Lp(a) in serum are indicators of vascular pathology in AD or VAD, while the lowering of serum DHEA-S is a consequence of AD pathology.

Raised serum adenosine deaminase level in nonobese type 2 diabetes mellitus.

The role of inflammation being minimal in the pathogenesis of type 2 diabetes mellitus (T2DM) in nonobese patients; the aim of the study was to investigate the role of adenosine deaminase (ADA) and see its association with diabetes mellitus. The preliminary case control study comprised of 56 cases and 45 healthy controls which were age and sex matched. 3 mL venous blood samples were obtained from the patients as well as controls after 8-10 hours of fasting. Serum ADA and routine biochemical parameters were analyzed. Serum ADA level was found significantly higher among nonobese T2DM subjects with respect to controls (38.77 ± 14.29 versus 17.02 ± 5.74 U/L; P < 0.0001). Serum ADA level showed a significant positive correlation with fasting plasma glucose (r = 0.657; P < 0.0001) level among nonobese T2DM subjects, but no significant correlation was observed in controls (r = -0.203; P = 0.180). However, no correlation was observed between serum ADA level compared to BMI and HbA1c levels. Our study shows higher serum ADA, triglycerides (TG) and fasting plasma glucose (FPG) levels in nonobese T2DM patients, and a strong correlation between ADA and FPG which suggests an association between ADA and nonobese T2DM subjects.