Grape Polyphenols Prevent Fructose-Induced Oxidative Stress and Insulin Resistance in First-Degree Relatives of Type 2 Diabetic Patients

OBJECTIVE

To assess the clinical efficacy of nutritional amounts of grape polyphenols (PPs) in counteracting the metabolic alterations of high-fructose diet, including oxidative stress and insulin resistance (IR), in healthy volunteers with high metabolic risk.

RESEARCH DESIGN AND METHODS

Thirty-eight healthy overweight/obese first-degree relatives of type 2 diabetic patients (18 men and 20 women) were randomized in a double-blind controlled trial between a grape PP (2 g/day) and a placebo (PCB) group. Subjects were investigated at baseline and after 8 and 9 weeks of supplementation, the last 6 days of which they all received 3 g/kg fat-free mass/day of fructose. The primary end point was the protective effect of grape PPs on fructose-induced IR.

RESULTS

In the PCB group, fructose induced 1) a 20% decrease in hepatic insulin sensitivity index (P < 0.05) and an 11% decrease in glucose infusion rate (P < 0.05) as evaluated during a two-step hyperinsulinemic-euglycemic clamp, 2) an increase in systemic (urinary F2-isoprostanes) and muscle (thiobarbituric acid–reactive substances and protein carbonylation) oxidative stress (P < 0.05), and 3) a downregulation of mitochondrial genes and decreased mitochondrial respiration (P < 0.05). All the deleterious effects of fructose were fully blunted by grape PP supplementation. Antioxidative defenses, inflammatory markers, and main adipokines were affected neither by fructose nor by grape PPs.

CONCLUSIONS

A natural mixture of grape PPs at nutritional doses efficiently prevents fructose-induced oxidative stress and IR. The current interest in grape PP ingredients and products by the global food and nutrition industries could well make them a stepping-stone of preventive nutrition.The Western diet, dominated by ultra-processed products rich in saturated fats and sugar, including high-fructose corn syrup, and poor in micronutrients (1), is a major contributor to the worldwide “diabesity” epidemic. In addition to contributing to calorie overconsumption, the unique metabolism of fructose (2) and its marked effect on systemic oxidative stress (3) could give it a pivotal role in the pathophysiology of insulin resistance (IR) and the metabolic syndrome (4).The “French Paradox,” defined as a low incidence of coronary heart disease despite consumption of a diet rich in saturated fat (5), has stimulated interest in investigating whether grape polyphenols (PPs) may offer antioxidant-consequential health benefits (6–8) including improved insulin sensitivity (9), although this effect remains debated (10). If this outcome were to be confirmed in humans, then supplementation of highly processed foods with grape PPs may prove to be a promising strategy to stem the tide of chronic metabolic diseases, which, furthermore, would be quite easy to implement, since PPs are currently marketed in the form of dyes and tannins that can be used safely in relatively large amounts in sugary foods (11).We thus designed a randomized double-blinded controlled study to assess the clinical efficacy of nutritional amounts of grape PPs in counteracting the metabolic effects of high-fructose diet (HFrD) to substantiate the hypothesis that by neutralizing oxidative stress, grape PPs can prevent fructose-induced IR.     

Abnormal steroidogenesis in three patients with Antley–Bixler syndrome: Apparent decreased activity of 17α-hydroxylase, 17,20-lyase and 21-hydroxylase

BACKGROUND: Antley-Bixler syndrome (ABS) is characterized mainly by abnormal skeletal morphogenesis such as craniosynostosis and radiohumeral synostosis, and by ambiguous genitalia in some cases. The mechanisms resulting in these deformities have not been determined. Methods: The adrenal and gonadal function of three Japanese ABS patients were evaluated. Patient 1 (17-year-old-male) had bilateral cryptoorchidism, delayed puberty and symptoms of glucocorticoid deficiency. Patient 2 (14-year-old male) and patient 3 (4-year-old female) presented with emaciation. Additionally, patient 3 had partial labial fusion and common urogenital sinus. In each patient, blood sampling for steroid analysis before and after rapid adrenocorticotropic hormone (ACTH) stimulation was carried out. Additionally, urinary steroids were quantified. Molecular analysis of CYP17 and CYP21A2 were also performed. Results: All patients showed elevated basal 17alpha-deoxysteroid levels. Although the 17alpha-deoxysteroid levels further increased after rapid ACTH stimulation, 17alpha-hydroxysteroids including cortisol did not respond, suggesting impaired 17alpha-hydroxylation. Patient 1 and patient 2 showed low adrenal androgen blood levels both before and after rapid ACTH stimulation. Patient 3 showed lower than normal excretions of urinary androgens. Additionally, a prolonged ACTH stimulation in patient 3 failed to elicit significant increase of adrenal androgens. These findings suggested impaired 17,20-lyase activity. In contrast to attenuated 17alpha-hydroxycorticosteroids, notably cortisol, elevated 17alpha-hydroxyprogesterone (17OHP) levels were observed, not only in pubertal patients (1 and 2) but also in prepubertal patient 3, indicating impaired 21-hydroxylation. This assumption was supported by increased urinary 21-deoxycortisol metabolite excretion in patients 2 and 3. With the exception of a heterozygous mutation of CYP17 in one of the patients, other mutations of this gene or CYP21A2 were identified in any of the patients. CONCLUSION: Combined decreased 17alpha-hydroxylation, 17,20-lyase activity and 21-hydroxylation was detected in three ABS patients. Considering that the enzymes responsible are all cytochrome P450 enzymes and that another cytochrome P450 enzyme, lanosterol 14alpha-demethylase, has recently been shown to be impaired in an ABS patient, we speculate that dysfunction of a system which commonly regulates cytochrome P 450 activity may be responsible for the ABS phenotype.     

Effect of Transfer Factor Therapy on Mixed Lymphocyte Culture Reactivity

We have studied the effect of dialyzable transfer factor therapy on three patients with immunodeficiency disease and in one patient who demonstrated no evidence of deficiency of either humoral or cellular immunity. We found evidence for nonspecificity in the effect of transfer factor on mixed lymphocyte culture reactivity. The data suggest that in patients with immunodeficiency disease a maturation of lymphocytes may lead to a generalized increased immune responsiveness. More profoundly, our data show that transfer factor may induce changes in the expression of histocompatibility determinants. We observed changes in the expression of determinants capable of stimulating in the mixed lymphocyte culture reaction as well as an increase in the capacity of lymphocytes to respond.     

Neurotropic Virus-Host Relationship Alterations Due to Variation in Viral Genome as Studied by Electron Microscopy

A series of experiments has been described in which litters of suckling rats were inoculated either with wild-type reovirus type III or one of two of its temperature-sensitive (ts) mutants. While the wild-type virus produced an acute, fatal syndrome, the ts mutants were substantially less neurovirulent. Of the ts mutant-inoculated animals, a large percentage of the surviving (chronic) animals given ts mutant B showed an unobstructive hydrocephalus ex vacuo whereas chronic ts mutant C animals showed no visible nervous system disease. The ts mutants persisted within the central nervous system (CNS) for 6 to 8 weeks, after which they could not be detected either virologically, immunologically or morphologically. In another set of experiments, organized CNS explants were studied following infection with either measles virus or the neuroadapted Mantooth strain of SSPE virus, a variant of measles. Wild measles (Edmonston strain) exerted an acute destructive effect, but SSPE virus had a tendency to enter into coexistence with the tissue without destroying its organotypic nature. These relationships are somewhat reminiscent of the neuropathologic conditions caused by these two viruses in man. Since the reovirus type III ts mutants possess both genetic and morphologic defects and in many instances cause CNS conditions different from that induced by the wild-type virus, it has been proposed that a comparable situation may exist after measles and SSPE virus infection. SSPE virions of the strain studied were found to be defective in certain viral components which may have contributed to the lower neurovirulence and its entering into a chronic relationship with the CNS, in contrast to the acute destructive nature of measles infection. The findings are discussed in terms of relevance to other chronic CNS diseases, particularly multiple sclerosis, in which the possiblity exists that a mutant virus is operative.     

The long term culture of bulk-isolated bovine oligodendroglia from adult brain

Oligodendroglia isolated from adult bovine brain by the method of Farooq et al. could be plated on polylysine-coated plastic dishes with an efficiency of 55–80%, and maintained in culture for as long as 4 months. The addition of cytosine arabinoside to the nutrient medium resulted in cultures that were approximately 90% oligodendroglia and 10% large fibroblasts. From 50 g of white matter 100 − 160 × 10⁶ oligodendroglia, containing approximately 6–10 mg protein, could be obtained in culture. These small round cells started to send out processes at 5 days in vitro and by 2 weeks they formed an extensive network of processes. By immunofluorescence, all cells of this morphology were positive for galactocerebroside (GC) and myelin basic protein (MBP), and negative for glial filament protein and fibronectin. Most of the large flat cells were positive for fibronectin and negative for GC, MBP and glial filament protein. As the cultures aged the oligodendroglia tented to clump and blebs formed on the surface of both perikarya and processes. By 4 months they showed evidence of degeneration and detached from the substrate. Electron microscopic examination showed that the cells had the appearance typical of oligodendroglia in situ. The somata were round to elliptical, with eccentrically placed nuclei, and were larger than freshly isolated cells. They grew directly on the substrate or on the surface of the fibroblasts. In older cultures the cells formed tight nests. The somata were enveloped by sheets of oligodendrocyte cytoplasm, sometimes having a myelin-like appearance. Gap junctions and small desmosomes were seen between oligodendroglial processes and between oligodendroglia and fibroblasts. The cytoplasm was characterized by a prominent Golgi apparatus, many mitochondria and lysosomes, scattered rough endoplasmic reticulum, free ribosomes, frequent centrioles and an abundance of microtubules. In cells from older cultures large vacuoles were common, and rarely they had multilamellar walls with alternating major and minor dense lines resembling myelin.     

Antisera to different glycolipids induce myelin alterations in mouse spinal cord tissue cultures

To study the demyelinative effects of antibodies to glycolipids, well-myelinated cultures of mouse spinal cord tissue were exposed to antisera against galactocerebroside and two gangliosides (GM₁ and GM₄), as well as to anti-white matter antiserum. The demyelinative process was evaluated by morphologic and biochemical techniques. Cultures exposed to anti-white matter and anti-galactocerebroside antisera showed the most marked changes. These consisted of a decrease in the number of oligodendroglial cells and dissolution and phagocytosis of myelin. Concomitantly, the activity of 2′,3′-cyclic nucleotide-3′-phosphohydrolase (CNPase) was decreased by 60–70%. This occured within 24 h of exposure to a relatively low concentration of serum (10%). Cultures exposed to anit-GM₁ and anti-GM₄ antisera showed similar changes but to a lasser degree. The CNPase activity was decreased about 30% within 48 h of exposure to a 25% concentration of these antisera. This diminution represents about a 20% loss of myelin, an observation corroborated by electron microscopy where myelin but not oligodendroglial cell was observed. Therefore, in addition to anti-galactocerebroside activity, which was previously found to be the major antibody responsible for the demyelinating activity induced by anti-whole CNS tissue antiserum, these data suggest that antibodies to gangliosides like GM₁ and GM₄ might also play a role in immune-mediated demyelination, including perhaps, the human demyelinating diseases.