Fructose Phosphorylation and Dephosphorylation by the Intestinal Mucosa of the Rat During Fructose Absorption

The role of phosphorylation in the absorption of fructose from the intestinal tract of the fasted rat by in vitro and in vivo techniques was studied. The authors' method for the determination of fructose phosphate esters was used and these esters were identified by paper chromatography and copper reduction techniques. Buffered homogenate of intestinal mucosa of a fasted rat, mixed with ATP, MgCl2, KF and fructose, when incubated at 30°, showed the formation of fructose-6-phosphate and fructose-1, 6-diphosphate at a rate that corresponded to the decrease in free fructose. The same homogenate, mixed with fructose-1, 6-diphosphate and incubated at 37°, showed the formation of fructose-6-phosphate and free fructose at a rate that corresponded to the decrease in the concentration of the diphosphate ester. Following intraduodenal injection of fructose solution into anesthetized fasted rats, homogenates of the intestinal mucosa showed the presence of fructose-6-phosphate and fructose-1, 6-diphosphate in average concentrations 14 and 5 times, respectively, those found in control muocsa, also concentrations of free fructose in the blood of the portal vein up to 24.6 mg % were observed. The large increase in fructose phosphate esters in the intestinal mucosa, observed after fructose administration, suggests that phosphorylation of sugars in absorption serves a more extensive function than to initiate glycolysis for the normal metabolism of the mucosal cells. The data obtained suggest that phosphorylation and dephosphorylation are functional steps in the absorption of fructose from the alimentary tract of the rat.

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A Molecular Approach to Immunoscintigraphy: A Study of the T-Antigen Conformation on the Surface of Tumors

Nuklearmedizin ◽

10.1055/s-0038-1624353 ◽

1987 ◽

Vol 26 (01) ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

S. Selvaraj ◽

M. R. Suresh ◽

G. McLean ◽

D. Willans ◽

C. Turner ◽

...

Keyword(s):

Monoclonal Antibodies ◽

Tumor Cell ◽

T Antigen ◽

Human Carcinomas ◽

Animal Tumor ◽

Synthetic Antigens

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both a and ß configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the β configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

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Factors affecting in vitro and in vivo antioxidant effects. Experimental conditions and nature of oxidants determine antioxidant efficacy

Journal of Berry Research ◽

10.3233/jbr-200695 ◽

2021 ◽

pp. 1-9

Author(s):

Etsuo Niki

Keyword(s):

Biological Molecules ◽

Experimental Conditions ◽

Factors Affecting ◽

Beneficial Effects ◽

Multiple Oxidants ◽

Antioxidant Effects

Reactive oxygen and nitrogen species have been implicated in the onset and progression of various diseases and the role of antioxidants in the maintenance of health and prevention of diseases has received much attention. The action and effect of antioxidants have been studied extensively under different reaction conditions in multiple media. The antioxidant effects are determined by many factors. This review aims to discuss several important issues that should be considered for determination of experimental conditions and interpretation of experimental results in order to understand the beneficial effects and limit of antioxidants against detrimental oxidation of biological molecules. Emphasis was laid on cell culture experiments and effects of diversity of multiple oxidants on antioxidant efficacy.

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THE ROLE OF A 3-0 SULFO GROUP IN THE GLUCOSAMINE RESIDUE OF A SYNTHETIC OLIGOSACCHARIDE FOR THE DETERMINATION OF ANTITHROMBOTIC ACTIONS

10.1055/s-0038-1644181 ◽

1987 ◽

Author(s):

J M Walenga ◽

J Fareed ◽

M Petitou ◽

J C Lormeau ◽

M Samama ◽

...

Keyword(s):

Sulfo Group ◽

Factor Xa ◽

Antithrombotic Effect ◽

Antithrombotic Activity ◽

Thrombosis Model ◽

Factor Xa Inhibition

We have previously reported on the antithromboticaction of a chemically synthesized heparin pentasaccharide which exhibits high affinity to anti thrombinIII and sole anti-factor Xa activity. In order to investigate the relative importance of the 3-0 sulfo group of this pentasaccharide, we evaluated the in vitro and in vivo antithrombotic activity of a synthetic pentasccharide devoid of the sulfo group at the third position of the glucosamine residue. In amidolytic and clot-based assays the 3-0 de- sulfated pentasaccharide (3-0-DP) failed to exhibit any antifactor Xa actions at concentrations <100 ug/ml in humanor rabbit plasmas, whereas pentasaccharide showed strong factor Xa inhibition at 1.0 ug/ml IK-=3.2x10 M)and at 10.0 ug/ml in rabbit plasma (K.=9.0×10™7 M). Using a rabbit stasis thrombosis model in which thrombosis was induce by human serum or an activated pro-thrombin complex concentrate, 3-0-DP failed to produce any antithrombotic action in acute intravenous regimens at dosages up to 200 ug/kg. In these two models, pentasaccharide produced >80% inhibition of induced thrombosis. These studies demonstrate the critical importance of the 3-0 sulfo group in this heparin pentasaccharide for the determination of antithrombotic activity, and that in this type of oligosaccharide, anti-factor Xa activity is responsible for producing the antithrombotic effect.

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The Role of Microscopy in Understanding Atherosclerotic Lysosomal Lipid Metabolism

Microscopy and Microanalysis ◽

10.1017/s1431927603030010 ◽

2003 ◽

Vol 9 (1) ◽

pp. 54-67 ◽

Cited By ~ 20

Author(s):

W. Gray Jerome ◽

Patricia G. Yancey

Keyword(s):

Cultured Cells ◽

Foam Cell ◽

Critical Role ◽

Cell Formation ◽

Foam Cell Formation ◽

Cholesteryl Esters ◽

Normal Metabolism

Microscopy has played a critical role in first identifying and then defining the role of lysosomes in formation of atherosclerotic foam cells. We review the evidence implicating lysosomal lipid accumulation as a factor in the pathogenesis of atherosclerosis with reference to the role of microscopy. In addition, we explore mechanisms by which lysosomal lipid engorgement occurs. Low density lipoproteins which have become modified are the major source of lipid for foam cell formation. These altered lipoproteins are taken into the cell via receptor-mediated endocytosis and delivered to lysosomes. Under normal conditions, lipids from these lipoproteins are metabolized and do not accumulate in lysosomes. In the atherosclerotic foam cell, this normal metabolism is inhibited so that cholesterol and cholesteryl esters accumulate in lysosomes. Studies of cultured cells incubated with modified lipoproteins suggests this abnormal metabolism occurs in two steps. Initially, hydrolysis of lipoprotein cholesteryl esters occurs normally, but the resultant free cholesterol cannot exit the lysosome. Further lysosomal cholesterol accumulation inhibits hydrolysis, producing a mixture of cholesterol and cholesteryl esters within swollen lysosomes. Various lipoprotein modifications can produce this lysosomal engorgement in vitro and it remains to be seen which modifications are most important in vivo.

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Immunocytochemical Determination of the Role of Alveolar Macrophages in Endotoxin Processing in vitro and in vivo

International Archives of Allergy and Immunology ◽

10.1159/000235486 ◽

1991 ◽

Vol 96 (2) ◽

pp. 149-155

Author(s):

George E. Keller, III ◽

Richard D. Dey ◽

Robert Burrell

Keyword(s):

Alveolar Macrophages

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Changes in erythrocyte deformability during day and possible role of melatonin

Endocrine Regulations ◽

10.2478/enr-2018-0003 ◽

2018 ◽

Vol 52 (1) ◽

pp. 17-20 ◽

Cited By ~ 1

Author(s):

Rastislav Vazan ◽

Katarina Plauterova ◽

Gabriela Porubska ◽

Jana Radosinska

Keyword(s):

Erythrocyte Deformability ◽

Diurnal Changes ◽

Sample Collection ◽

Pass Through ◽

In Vivo Effects ◽

Vitro Effect

Abstract Objectives. The deformability of erythrocytes is their ability to change shape in order to pass through the capillaries. Th is is necessary for quality of microcirculation and sufficient delivery of oxygen to the tissues. Th e aim of our study was to investigate the possible spontaneous changes in the erythrocyte deformability during day and evaluation of the possible direct effects of melatonin (hormone involved in regulation of biorhythms) on the erythrocyte deformability. Methods. Samples of capillary blood were taken from 12 healthy volunteers in the morning (8:00) and early in the evening (16:30). Determination of erythrocyte deformability was done based on the measurement of their filtrability. It was measured immediately aft er the sample collection and 2-hour lasting incubation without or with melatonin (2000 μmol/L). Results. Erythrocyte deformability was significantly lower in the morning (filtrability index: 0.68±0.01 morning vs. 0.71±0.01 early evening, p<0.05). Th e incubation of blood samples with melatonin did not have impact on deformability. Conclusions. We suggest the presence of diurnal changes in erythrocyte deformability with worse values in the morning that may contribute to higher risk of ischemic attacks in the morning hours. Direct in vitro effect of melatonin on deformability was not observed, but possible in vivo effects cannot be excluded.

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5,6-Dihydroxyindole-2-carboxylic acid is incorporated in mammalian melanin

Biochemical Journal ◽

10.1042/bj2860491 ◽

1992 ◽

Vol 286 (2) ◽

pp. 491-495 ◽

Cited By ~ 54

Author(s):

K Tsukamoto ◽

A Palumbo ◽

M D'Ischia ◽

V J Hearing ◽

G Prota

Keyword(s):

Carboxylic Acid ◽

Carboxyl Groups

The role of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) in the biosynthesis of melanins has been studied by using the incorporation of specifically radiolabelled melanogenic precursors into melanins formed by melanocytes growing in vitro and in vivo. Extracts of mouse melanocytes and intact viable melanocytes were found to incorporate into melanin from 25% to more than 60% of [1-14C]tyrosine. Melanins from melanoma tumours grown in mice were radiolabelled with 3,4-dihydroxy[1-14C]phenylalanine, purified and chemoselectively decarboxylated. Determination of the 14CO2 evolved showed that at least 20% of the precursor incorporated in vivo retains the label in the form of non-aminoacidic aromatic-type carboxyl groups. These results provide the first unambiguous demonstration that DHICA is incorporated in physiologically relevant amounts in mammalian melanins.

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The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000116 ◽

2012 ◽

Vol 82 (3) ◽

pp. 228-232 ◽

Cited By ~ 7

Author(s):

Mauro Serafini ◽

Giuseppa Morabito

Keyword(s):

Antioxidant Capacity ◽

Dietary Intervention ◽

Ex Vivo ◽

The Body ◽

Dietary Polyphenols ◽

Enzymatic Antioxidant ◽

Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

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