Estimation of dehydroascorbic acid in blood of diabetic patients
TL;DR: The DHA from diabetic blood has been isolated as the 2,4-dinitrophenylhydrazone derivative and identified by thin-layer chromatography and spectrophotometry.
About: This article is published in Analytical Biochemistry.The article was published on 1979-10-01. It has received 77 citations till now. The article focuses on the topics: Dehydroascorbic acid & Ascorbic acid.
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TL;DR: The discovery that pentosidine can form not only from pentoses but also from hexoses and ascorbate raises major new questions concerning biochemical pathways of the Maillard reaction in vivo.
465 citations
TL;DR: GLUT1 and GLUT3 isoforms are the specific glucose transporter isoforms which mediate DHA transport and subsequent accumulation of AA according to Xenopus laevis oocyte expression system studies.
431 citations
TL;DR: In this paper, the intake of antioxidants was studied for its ability to predict type 2 diabetes in a cohort of 2,285 men and 2,019 women 40-69 years of age and free of diabetes at baseline (1967-1972).
Abstract: OBJECTIVE —The intake of antioxidants was studied for its ability to predict type 2 diabetes. RESEARCH DESIGN AND METHODS —A cohort of 2,285 men and 2,019 women 40–69 years of age and free of diabetes at baseline (1967–1972) was studied. Food consumption during the previous year was estimated using a dietary history interview. The intake of vitamin C, four tocopherols, four tocotrienols, and six carotenoids was calculated. During a 23-year follow-up, a total of 164 male and 219 female incident cases occurred. RESULTS —Vitamin E intake was significantly associated with a reduced risk of type 2 diabetes. The relative risk (RR) of type 2 diabetes between the extreme quartiles of the intake was 0.69 (95% CI 0.51–0.94, P for trend = 0.003). Intakes of α-tocopherol, γ-tocopherol, δ-tocopherol, and β-tocotrienol were inversely related to a risk of type 2 diabetes. Among single carotenoids, β-cryptoxanthin intake was significantly associated with a reduced risk of type 2 diabetes (RR 0.58, 95% CI 0.44–0.78, P CONCLUSIONS —This study supports the hypothesis that development of type 2 diabetes may be reduced by the intake of antioxidants in the diet.
380 citations
TL;DR: Immunohistochemical localization studies revealed that pyrraline is found predominantly in the sclerosed extracellular matrix of glomerular and arteriolar renal tissues from both diabetic and aged nondiabetic individuals, suggesting that molecular damage by advanced Maillard reaction products may be a common mechanism in their development.
Abstract: Recent progress in structure elucidation of products of the advanced Maillard reaction now allows probing specifically for the role of this reaction in the pathogenesis of age- and diabetes-related complications. Pyrraline is a glucose-derived advanced glycation end product against which polyclonal and monoclonal antibodies have been raised. Immunohistochemical localization studies revealed that pyrraline is found predominantly in the sclerosed extracellular matrix of glomerular and arteriolar renal tissues from both diabetic and aged nondiabetic individuals. Pentosidine and carboxymethyllysine are Maillard end products derived from both glucose and ascorbate. In addition, pentosidine can be formed from several other sugars under oxidative conditions, and in vitro studies suggest that a common intermediate involving a pentose is a necessary precursor molecule. The highest levels of these advanced Maillard products are generally found in the extracellular matrix, but these products are also present in lens proteins and in proteins with a fast turnover such as plasma proteins. Diabetes, and especially uremia, greatly catalyzes pentosidine formation. Both conditions are characterized by accelerated cataractogenesis, atherosclerosis, and neuropathy, suggesting that molecular damage by advanced Maillard reaction products may be a common mechanism in their development.
313 citations
TL;DR: A high correlation betweenpentosidine levels and long-wave collagen-linked fluorescence also was observed, suggesting that pentosidine is a generalized marker of accelerated tissue modification by the advanced glycosylation/Maillard reaction, which is enhanced in IDDM patients with severe complications.
Abstract: Pentosidine is an advanced glycosylation end product and protein cross-link that results from the reaction of pentoses with proteins. Recent data indicate that long-term glycation of proteins with glucose also leads to pentosidine formation through sugar fragmentation. In this study, the relationship between the severity of diabetic complications and pentosidine formation was investigated in collagen from skin-punch biopsies from 25 nondiabetic control subjects and 41 IDDM patients with diabetes duration >17 yr. Pentosidine was significantly elevated in all IDDM patients versus control subjects ( P P P P P P P P > 0.05). A high correlation between pentosidine levels and long-wave collagen-linked fluorescence also was observed, suggesting that pentosidine is a generalized marker of accelerated tissue modification by the advanced glycosylation/Maillard reaction, which is enhanced in IDDM patients with severe complications.
300 citations
Cites background from "Estimation of dehydroascorbic acid ..."
...Favoring this possibility is the discovery of elevated dehydroascorbate levels in the plasma of diabetic individuals (23-25)....
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TL;DR: Rat pancreatic islets have been studied following successive daily administration of dehydroascrobic acid (DHA) and during the recovery phase following 3 daily injections, and few secretory granules remain in B cell cytoplasm, but the cells have prominent granular ER and a Golgi apparatus with numerous prosecretorygranules.
Abstract: Rat pancreatic islets have been studied following successive daily administration of dehydroascrobic acid (DHA) and during the recovery phase following 3 daily injections. One injection of DHA produces degranulation of B cells seen in the light microscope as a loss of aldehyde fuchsin positivity. In the electron microscope the B cells appear to have secretory granules accumulated subjacent to the plasma membranes. Following 2 and 3 daily injections, B cells evidence alterations in the organization of the granular endoplasmic reticulum and mitochondria, and secretory granules are scant but when present are subjacent to the plasma membrane. After 5 to 7 days' recovery few secretory granules remain in B cell cytoplasm, but the cells have prominent granular ER and a Golgi apparatus with numerous prosecretory granules. The primary effect of DHA is an exaggerated secretory response of B cells, which is intensified with subsequent injections. Necrosis of B cells as produced by alloxan is not seen.
27 citations
TL;DR: A reduction in the activity of this DHA reductase system could contribute towards the lowered plasma levels of ascorbic acid known to occur in pernicious anaemia.
19 citations
TL;DR: The Roe and Kuether method' for the estimation of dehydro-L-ascorbic acid (DHA) in tissues has been modified in the laboratory to permit the estimation at low concentrations of this acid when present in low concentrations.
Abstract: The Roe and Kuether method' for the estimation of dehydro-L-ascorbic acid (DHA) in tissues has been modified in our laboratory to permit the estimation of this acid when present in low concentrations. The normal procedure with many plant tissues yields extracts that contain less than 0.25 to 0.5 pg./ml. after dilution with the phenylhydrazine reagents; even lower values are encountered if the tissue is exposed to anaerobic or partially anaerobic conditions before extraction. Moreover many metaphosphoric acid extracts of plant tissues when treated with 85 per cent HzSOr, as in the Roe and Kuether method, develop brown colors on standing that absorb in the 530-mcc region, making it impossible to estimate the concentration of the hydrazone formed from DHA with any accuracy. The bis(dinitropheny1)hydrazone formed from DHA is virtually insoluble in the sulfuric-phenylhydrazine reagent, and may be collected quantitatively from large volumes of extract by centrifugation and/or filtration. In this way the hydrazone may be concentrated and, a t the same time, separated from other undesirable constituents of the tissue, thus increasing the accuracy of the estimation. The preliminary procedure of Roe and Kuether is followed through to the stage of incubation of the extract with the phenylhydrazine reagents. Since we were attempting to estimate small amounts of DHA in the presence of a large amount of ascorbic acid, we found it advisable (although thiourea was present) to remove with nitrogen all oxygen from the solution before incubating the extract in order to prevent any possible oxidation of ascorbic acid. After incubation for 3 hours a t 37\" C., the solution is centrifuged a t 20,000 g for 30 min. to aggregate the insoluble hydrazones. These are collected by filtration through sintered glass filters, and the collected precipitate washed with 0.1 N HzS04 to remove the unchanged 2,4dinitrophenylhydrazine. The washed hydrazones are dissolved in a small volume of ethyl acetate, and the solution transferred to a separating funnel. If, as in many plant extracts, hydrazones of the a-0x0 acids are also present, these may with advantage be removed a t this stage by extracting the ethyl acetate solution twice with a saturated solution of NaHC03. By this treatment thesea-oxo acid hydrazones dissolve in the aqueous phase, while the hydrazone derivative of DHA remains in the nonaqueous phase. After careful separation, the nonaqueous phase is concentrated in vacuo to dryness. The hydrazones are taken up in 1 ml. of ethyl acetate to which is added 5 ml. of HzS04 50 per cent w/v. After standing for 30 to 60 min. at room temperature the concentration of the hydrazone is determined from the difference between the absorption a t 530 mp of this solution and a similar solution in which the
11 citations
TL;DR: The main lesions occurring as a result of injection of IDHA, those in the islets of Langerhans, are thus very similar to the lesions of experimental alloxan diabetes, but it appears that for comparable islet damage, DHA produces higher blood sugar concentrations.
Abstract: 1. Rats made hyperglycaemic by repeated intravenous injections of dehydroascorbic acid (DHA) were killed 24 hrs. (Group 1) and four days (Group 2) after the last DHA injection, and the pancreas, kidneys, liver, adrenals and thyroid were examined histologically.
2. The most marked lesions were found in the islets of Langerhans of the pancreas. In Group 1 animals there was degranulation and shrinkage of the β-cells, pyknosis of their nuclei, and occasionally vacuolation of their cytoplasm; rarely, actual disintegration of cells was observed. No glycogen was stainable in the β-cells. In Group 2 rats the islets were small: the β-cells were reduced in numbers, shrunken and usually agranular, with pyknotic nuclei. Cytoplasmic vacuolation was obvious, and though some glycogen was demonstrable in the cells, all the vacuolation could not be accounted for in this way.
3. The kidneys showed no significant degenerative change in either group, but there was some glycogen storage in the tubular cells of Group 2 rats.
4. In the adrenal cortices, a reduction of Sudanophil and Feulgenpositive material was observed in the zona glomerulosa and the zona fasciculata in the males of both groups, while no such change could be demonstrated in the females of Group 2.
5. No change of note was found in the livers or thyroids of the experimental animals.
6. The main lesions occurring as a result of injection of IDHA, those in the islets of Langerhans, are thus very similar to the lesions of experimental alloxan diabetes, but it appears that for comparable islet damage, DHA produces higher blood sugar concentrations.
8 citations