Biomedical subjects

N Santanam

Publications and source records attributed to N Santanam.

36 records · Page 2Linked to original sources

PubMed1998

Generation and characterization of a polyclonal antipeptide antibody to human glycodelin.

OBJECTIVE: To develop and characterize an antiglycodelin antibody using a 15-amino acid synthetic peptide as antigen, derived from the sequence of human glycodelin. DESIGN: We have developed a chicken antiglycodelin-derived peptide antibody and have characterized the antibody with the use of endometrial and ovarian cell lines. The antibody was also tested for its ability to detect glycodelin by ELISA assay, immunocytochemistry, and by Western blot. SETTING: Various cell lines, cell culture medium, and amniotic fluid were used in the experiments. PATIENT(S): Amniotic fluid was collected from pregnant patients in their first trimester of pregnancy. INTERVENTION(S): No intervention. MAIN OUTCOME MEASURE(S): Detection of glycodelin. RESULT(S): The cell lines RL95-2 (human endometrial carcinoma cells), OVCAR-3 (human ovarian adenocarcinoma cells), HeLa (human cervical epitheloid carcinoma cells), and EM42-D (human endometrial epithelial cells) reacted with the antibody, indicating the presence of glycodelin. A specific 45-kd protein representing glycodelin was detected by Western blot in the amniotic fluid. CONCLUSION(S): Antipeptide antibodies can be successfully used to detect and quantify the presence of glycodelin in cells and fluids.

Adenocarcinoma↗

PubMed1998

Endometriosis: a disease of oxidative stress?

Our central hypothesis proposes that oxidatively damaged red blood cells (RBCs), apoptotic endometrial cells or undigested endometrial tissue may signal the recruitment and activation of mononuclear phagocytes. Women with endometriosis are prone to respond to this stimulus with an inadequate macrophage scavenger receptor response although the secretory response is not impaired. Activated macrophages in the peritoneal cavity generate an oxidative stress, which consists of lipid peroxides, their degradation products, and products formed from their interaction with low-density lipoprotein (LDL) apoprotein and other proteins. The lipoproteins of the peritoneal fluid (interstitial fluid) have been shown to have lower vitamin E levels and to be more readily oxidized than plasma, so peritoneal fluid may actually contribute to the disease process actively rather than as a passive carrier of mediators of inflammation and growth. As a result of such a stress, a sterile, inflammatory reaction with secretion of growth factors, cytokines, and chemokines is generated, which is deleterious especially to successful reproduction. We propose that such a pro-oxidant environment (peritoneal fluid as well as activated macrophages) promotes growth of ectopic endometrium. The data presented in this review are just the beginning of exploring the role of oxidative stress in mediating the pathophysiology of endometriosis. Only by understanding the mechanisms involved in the pathogenesis of endometriosis can we develop the basis for new diagnostic and therapeutic approaches.

Apoptosis↗

PubMed1998

Oxygen radicals, antioxidants, and lipid peroxidation.

Reactive oxygen species derived from molecular oxygen are highly reactive metabolites. These species can be generated by cellular or acellular mechanisms. They react with all biological molecules such as protein, lipid, and carbohydrates. The reaction of these species with lipids, called lipid peroxidation, is a very well-studied phenomenon. Compounds, which scavenge these molecules, are called antioxidants. The disruption of the delicate balance between pro- and antioxidants has been implicated in the pathophysiology of many chronic diseases such as, for example, atherosclerosis. This article presents an introduction to what reactive oxygen species are and their reactions with various metabolites. It deals with lipid peroxidation in detail and with methods for measuring lipid peroxidation. This article also outlines the importance of these species in the pathology of various gynecological diseases.

Antioxidants↗

PubMed1998

Exercise and cardiovascular disease: a new perspective.

The oxidation of low density lipoprotein (LDL) has been suggested as a key event in atherogenesis. Paradoxically, exercise, which imposes an oxidative stress, is an important deterrent of cardiovascular disease. In study 1 the oxidizability of LDL was enhanced in exercisers compared with sedentary controls. The lag time of isolated LDL subjected to copper-induced in vitro oxidation was significantly shortened in the exercisers compared with sedentary subjects. This increased sensitivity was not due to a decreased presence of vitamin E. Instead, these findings suggested that the LDL of exercisers may contain increased amounts of preformed lipid peroxides, which account for the increased oxidizability. In study 2, a group x sex ANOVA revealed that male exercisers had a significantly longer mean lag time than male sedentary subjects and that females had similar mean lag times regardless of exercise group. This remained the case when statistical adjustment was made for age, body mass index, blood lipid levels, LDL, and plasma alpha-tocopherol levels. Study 1 exercisers had been in training for a shorter time (< 1 year) than study 2 exercisers (> 2 years). These findings suggest that truly "chronic" exercise (aerobic intensity over several months) decreases the susceptibility of a male exerciser's LDL to undergo oxidation. Conversely, regular aerobic stress during an overall shorter time span creates a more oxidative environment in the body, thus increasing the susceptibility of LDL to undergo oxidation. The oxidative stress of aerobic exercise does not appear to adversely affect the oxidizability of LDL in women.

Adolescent↗

PubMed1998

Lysophosphatidyl choline, a chemotactic factor for monocytes/T-lymphocytes is elevated in endometriosis.

Inflammatory processes have been hypothesized to mediate some of the clinical sequelae associated with endometriosis. The peritoneal fluid (PF) of women with endometriosis is known to contain more inflammatory cells and their associated cytokines, chemokines, and growth factors. This work provides strong evidence for oxidative stress in the PF of women with endometriosis. 1) The low density lipoprotein (LDL) isolated from the PF of subjects with endometriosis shows a small but detectable increase in electrophoretic mobility compatible with mildly oxidized LDL compared with LDL isolated from the plasma of the same subjects and PF of controls. 2) Isolated PF-LDL of endometriosis subjects is more readily oxidized in vitro than PF-LDL of controls, or LDL isolated from plasma. 3) Vitamin E content is significantly lower in endometriosis PF compared with controls, and compared with plasma of women with endometriosis and controls. No difference is seen between plasma and PF of control subjects. 4) The ratio of phosphatidylcholine/lyso phosphatidylcholine (Ptd/lyso PtdCho) in the PF of endometriosis subjects is significantly lower compared with PF of controls. Taken together, these data provide strong evidence for a pro-oxidant environment in the peritoneal cavity of women with endometriosis. Lyso PtdCho, a product derived from phospholipase A2 action on peroxidized phosphatidylcholine and a potent chemotactic factor for monocytes and T-lymphocytes, is elevated in endometriosis. We hypothesize that the increased presence of lipid peroxidation products in the PF of endometriosis subjects may, at least partly, account for the recruitment of leukocytes, the increase in macrophage activation, the secretion of monocyte--macrophage-derived cytokines, and the endometrial growth-promoting activity associated with endometriosis.

Adolescent↗

PubMed1998

Implications of lag time concept in the oxidation of LDL.

Oxidation of low density lipoprotein (LDL) has been implicated in the pathogenesis of atherosclerosis. The most common technique for measuring the oxidation of lipoproteins is the continuous measurement of the formation of conjugated diene at OD 234 nm. The concept of "lag time", derived from such measurements, has been used to test the efficacy of various antioxidants for their ability to inhibit the oxidation of LDL. This review will elaborate on some of the factors that might affect the lag time.

Alkenes↗

PubMed1998

Estradiol as an antioxidant: incompatible with its physiological concentrations and function.

Estradiol has been documented to inhibit the oxidation of low density lipoprotein (LDL). We show that physiological concentrations of estradiol do not inhibit the oxidation of LDL by copper. LDL samples isolated from a) premenopausal and postmenopausal women and from b) women at different time periods during their menstrual cycle, who differ vastly in plasma estradiol levels, were also oxidized at the same rates by copper. In contrast, LDL samples isolated from c) women who were hyperstimulated during in vitro fertilization (IVF), with estradiol concentrations above 2000 pg/ml, were resistant to oxidation by copper. However, these LDL samples were also oxidized at a higher rate by peroxidases. More importantly, subjects with high estradiol levels also showed an increase in myeloperoxidase (MPO) protein in the plasma. Based on these results, we conclude that at physiologic concentrations, it is unlikely that estradiol could act as an antioxidant. In fact, the ability of estradiol to induce MPO and become a prooxidant might instead suggest that MPO-mediated oxidative clearance of LDL from plasma by liver might favorably influence the outcome of atherosclerosis.

Adult↗

PubMed1997

Aqueous extracts of cigarette smoke promote the oxidation of low density lipoprotein by peroxidases.

Oxidation of low density lipoprotein (LDL) by cigarette smoke has been considered a potential mechanism by which smoking may promote atherosclerosis. We report in this study that cigarette smoke extract (CSE) inhibited copper-induced oxidation of LDL suggesting the presence of antioxidants in CSE. It is currently believed that peroxidases may oxidize LDL in vivo and during such oxidations antioxidants become pro-oxidants. Accordingly, when LDL was oxidized by peroxidase in the presence of CSE there was an increase in the oxidation of LDL. This is the first study suggesting that smoking may promote atherosclerosis by enhancing peroxidase-catalyzed lipid peroxidation.

Copper↗

PubMed1997

Interaction of Interceed oxidized regenerated cellulose with macrophages: a potential mechanism by which Interceed may prevent adhesions.

OBJECTIVE: The objective of the study was to determine whether Interceed oxidized regenerated cellulose (Johnson & Johnson Medical, Arlington, Tex.), because of its polyanionic nature, may compete for the macrophage scavenger receptor. STUDY DESIGN: RAW macrophages were incubated with Interceed oxidized regenerated cellulose and known scavenger receptor ligands. The production of interleukin-1beta by mouse peritoneal macrophages was measured in the presence of Interceed cellulose. RESULTS: When macrophages were incubated with Interceed cellulose, increasing concentrations inhibited the uptake of fluorescent acetyl low-density lipoprotein. In the presence of Interceed cellulose there was a decrease in the production of interleukin-1beta by mouse macrophages. CONCLUSION: These results suggest that the interaction of Interceed oxidized regenerated cellulose with macrophages with scavenger receptors may result in a decreased secretion of matrix components, inflammatory mediators, and cellular growth factors. Thus Interceed cellulose may function as a biologic barrier in preventing adhesions.

Animals↗

PubMed1997

Generation of a polyclonal antibody against lipid peroxide-modified proteins.

A specific polyclonal antibody against the lipid peroxide (LOOH)-modified rabbit serum albumin (RSA) was generated in rabbits. The antibody selectively recognized the modified protein in a concentration-dependent manner and did not cross react with aldehyde-modified proteins or proteins directly oxidized with the free radical generator 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH). Oxidized low-density lipoprotein (Ox-LDL), but not native LDL, was also recognized by the antibody in a concentration-dependent manner. The antibody also cross reacted with several other proteins modified by LOOH suggesting that the antibody is directed towards a common epitope and not towards the protein sequence. Western blot analysis of normal human plasma showed that at least three different proteins are recognized by the antibody. RAW cells, preincubated with LOOH, were immunostained with the antibody and the antigenic epitopes were present intracellularly, while controls lacking in the primary antibodies failed to show immunoreactivity. Atherosclerotic arteries from cholesterol-fed monkeys and human atherosclerotic lesions were also immunostained by the antibody. The immunoreactivity was co-localized in areas rich in foam cell macrophages. These results suggest that LOOH-modified proteins present an unique antigenic epitope that may represent a primary product of interaction of LOOH with proteins.

Aldehydes↗

PubMed1996

The effect of RU 486 and related compounds on cultured macrophage differentiation and function.

OBJECTIVE: Our purpose was to examine RU 486 and related compounds on macrophage scavenger receptors and cellular adhesion. STUDY DESIGN: THP-1 cells were activated with phorbol myristate acetate and treated with dexamethasone, levonorgestrel, and RU 486 alone or in combination. Scavenger receptor activity was determined by counting adhered cells. In addition, fluorescently labeled acetyl low density lipoprotein uptake was determined. RESULTS: Both dexamethasone and RU 486 significantly decreased activated macrophages (81% and 26% of control). Levonorgestrel stimulated adherent cells in activated monocytes (130% of control). RU 486 and dexamethasone were antagonistic when combined (p < 0.001). In contrast, dexamethasone could not overcome the stimulatory effect of levonorgestrel (p < 0.001). Fluorescent studies yielded similar results. CONCLUSIONS: RU 486 is a known antiglucocorticoid with novel antioxidant properties. Levonorgestrel has antiglucocorticoid but no antioxidant activity. Glucocorticoids decrease scavenger receptors and antioxidants regulate inflammatory cytokines. RU 486 antagonized the inhibitory effect of dexamethasone on scavenger receptors, whereas levonorgestrel was stimulatory. It is therapeutically important to up-regulate scavenger receptor activity by antiglucocorticoids in the peritoneal cavity of women with endometriosis. However, because these mechanisms also induce inflammatory cytokines, a balance of antioxidants and antiglucocorticoids may prove beneficial.

Antioxidants↗

PubMed1996

Inhibition of oxidative modification of proteins by RU486.

OBJECTIVES: To elucidate further the antioxidant properties of RU486. We determined whether it can protect biologic molecules such as proteins (albumin, low-density lipoprotein [LDL] and oxidized LDL) from damage by pre-existing lipid peroxides. DESIGN: In vitro study. INTERVENTIONS: We tested the effects of RU486 on the formation of fluorescent oxidatively modified proteins by pre-existing lipid peroxides. We used two model systems, the incubation of oxidized linoleic acid with serum albumin and the incubation of human LDL with copper. MAIN OUTCOME MEASURES: The formation of modified protein was established by determining fluorescence at excitation wavelength of 330 nm and emission wavelength between 390 and 500 nm. Modified protein has a characteristic emission between 425 and 430 nm. RESULTS: The addition of increasing amounts of RU486 inhibited the formation of fluorescent oxidatively modified protein products in both model systems. CONCLUSION: These results provide evidence that RU486 not only can prevent the formation of lipid peroxide, but also can block the formation of fluorescent protein adducts in the presence of pre-existing lipid peroxides.

Antioxidants↗

PubMed1995

Paradoxical actions of antioxidants in the oxidation of low density lipoprotein by peroxidases.

Oxidation of LDL by peroxidases has been suggested to be a model for in vivo oxidation. The mechanism might involve the generation of an intermediate radical such as a phenoxy radical. We show that, in contrast to the oxidation of LDL by copper, oxidation by peroxidase system (H2O2/horse radish peroxidase) showed less resistance. This suggested that either the antioxidants were consumed more rapidly or might have actually participated in the oxidation. Accordingly, addition of vitamin E increased the rate of oxidation of LDL. In contrast, probucol inhibited the oxidation even at low concentrations suggesting ineffective formation of probucol radical or the sterically hindered probucol radical was inefficient in catalyzing subsequent oxidation. The oxidation of LDL by horse radish peroxidase was also enhanced in the presence of diphenylphenylenediamine, an antioxidant that does not have a phenolic -OH group. Myeloperoxidase was able to oxidize LDL even in the absence of added tyrosine suggesting that it was able to utilize the LDL-associated vitamin E. Addition of free tyrosine inhibited the formation of conjugated dienes. We suggest that if peroxidases are involved in the initiation of LDL oxidation in vivo, higher concentrations of antioxidants may be indicated to inhibit propagation of oxidation.

Antioxidants↗

PubMed1995

Inhibition of macrophage-dependent low density lipoprotein oxidation by nitric-oxide donors.

We have previously shown that nitric oxide donors inhibit the oxidation of low density lipoprotein (LDL) initiated by copper ions or by azo-bis-amidinopropane (Hogg et al., 1993. FEBS Lett. 334: 170-174). In this study, the nitric oxide donors S-nitroso-N-acetylpenicillamine (SNAP), spermine NONOate, and sodium nitroprusside were tested for their ability to inhibit macrophage-dependent oxidation of LDL. SNAP and spermine NONOate inhibited macrophage-dependent oxidation of LDL in a time- and concentration-dependent manner. We propose that nitric oxide is acting as a chain-breaking antioxidant that can inhibit the progression of lipid peroxidation in cell dependent-oxidation of LDL. By this mechanism nitric oxide could be an endogenous defense against atherogenesis. In contrast, sodium nitroprusside enhanced cell-mediated oxidation of LDL by a mechanism dependent on superoxide production and transition metal ions. Sodium nitroprusside also enhanced LDL oxidation by cell culture medium alone by a similar mechanism. The use of sodium nitroprusside as a nitric oxide donor in cellular systems appears to be complicated by the release of iron leading to an enhanced oxidative stress. Thus the effects of sodium nitroprusside in such systems may be unrelated to nitric oxide release.

Animals↗

PubMed1995

Cellular cysteine generation does not contribute to the initiation of LDL oxidation.

It has been suggested that the generation of cysteine (Cys-SH) by cells may play a role in the initiation of oxidation of low density lipoprotein (LDL). Cysteine has long been considered as an antioxidant. We studied the effect of Cys-SH on the oxidation of LDL by copper. The presence of Cys-SH had a profound inhibitory effect on the formation of conjugated dienes when fresh LDL was used. However, when we used LDL samples that were subjected to pre-incubation with copper, a progressive decrease in the inhibition and an actual enhancement of oxidation by Cys-SH could be demonstrated. The oxidation of freshly prepared LDL by RAW macrophages as compared to older LDL was considerably less. The addition of Cys-SH inhibited the oxidation of LDL by cells. In contrast, the addition of cystine (Cys-S-S) enhanced the oxidation of older LDL preparations while such additions had no effect on the oxidation of freshly prepared LDL. When pre-incubated LDL was subjected to oxidation by cells an enhancement of oxidation by Cys-S-S could be noted. These results demonstrate that the role of Cys-SH generated as a result of cellular recycling of Cys-S-S in the oxidation of LDL may not relate to the initiation of oxidation reactions. However, Cys-SH may enhance the rate of oxidation of LDL that may contain peroxides.

Antioxidants↗

PubMed1994

Mechanisms of oxidation, antioxidants, and atherosclerosis.

The oxidation of LDL by a number of different cell types has been studied and described. Cells may be able to initiate and seed peroxides in LDL but, in the absence of metals or peroxidase activity, may not be able to oxidize the lipoprotein. Monocyte-derived macrophages and neutrophils are able to initiate and propagate lipid peroxidation. The oxidative role of smooth muscle cells and endothelial cells may be restricted solely to the generation of hydrogen peroxide or other oxidants. The above rationale presents a problem in using LDL preparations that already contain peroxides, and in using media that generate peroxides independently of cells.

Animals↗

PubMedDate not supplied

Increased glycodelin levels in gynecological malignancies.

Glycodelin, an immunosuppressive protein with contraceptive properties, is synthesized by a variety of tissues and cell types. The ability of reproductive tissues to synthesize glycodelin is of major interest in pregnancy and disease conditions. We studied glycodelin levels in subjects with malignant gynecological tumors and in control subjects. Using a polyclonal glycodelin antibody against the synthetic glycodelin peptide sequence, an enzyme-linked immunosorbent assay (ELISA) was devised to measure plasma glycodelin levels. The assay detected as much as 5 ng/ml of glycodelin. There was a significant increase in plasma glycodelin levels in endometrial > ovarian > cervical cancer subjects when compared to those of controls. Strong expression of mRNA and protein were found in the ovarian and endometrial tumor tissues. Given glycodelin's immunosuppressive abilities, increased level of glycodelin may facilitate tumor growth in gynecological malignancies.

Adolescent↗

PubMedDate not supplied

Oxidative stress in cardiovascular disease.

The oxidative hypothesis of cardiovascular disease (CVD) has undergone tremendous changes during the past few years. Innumerable new proatherogenic effects have been added to the existing list that could be attributed to oxidative stress. However, both animal and human trials with a variety of antioxidants have failed to establish unambiguously a protective role for antioxidants in the prevention of CVD. This could be because of poor choice and dosage of antioxidants, incompatible experimental models, oxidative metabolism of the antioxidant, unrealistic expectations, and other reasons. More importantly, recent studies suggest that oxidative stress also could induce antioxidant enzymes in both cell culture and in vivo systems. In lieu of the potential of known deterrents of CVD such as exercise, estrogens, and the consumption of polyunsaturated fatty acids to induce an oxidative stress, the possibility that natural enhancement of antioxidant defense in the artery could better serve to deter CVD cannot be ignored. Thus, if oxidative stress does play a role in CVD, it may be better, in the absence of suitable animal models that respond to antioxidants, to adhere to behavioral and dietary changes that have been shown to benefit CVD.

Cardiovascular Diseases↗